Chapter XX: Appendix: “Rhizopods in Poliomyelitis acuta.” (14)

_Mermithidæ_, greatly elongated “Nematodes,” which, in the larval
stage, are parasitic in insects, but in their adult condition are
free living. Cuticle with diagonal striation. Without an open
mouth or anus. Oral papillæ present. Characteristic eggs with two
processes, ending in a tuft of filaments. Larvæ with a movable boring
spine at the head end.

_Gordiidæ._--Long, thread-like “Nematodes.” Mouth and anterior
portion of gut atrophied in adult. Oral papillæ absent.

THE NEMATODES OBSERVED IN MAN.

Family Sub-family Genus Species
_Anguillulidæ_ -- _Rhabditis_ _R. pellio._
_R. niellyi._
_Rhabditis sp._
_Anguillula_ _A. aceti._
_Anguillulina_ _A. putrefaciens._
_Angiostomidæ_ -- _Strongyloides_ _St. stercoralis._
_Gnathostomidæ_ -- _Gnathostoma_ _Gn. siamense._
_Gn. spinigerum._
_Dracunculidæ_ -- _Dracunculus_ _D. medinensis._
_Filariidæ_ _Filariinæ_ _Filaria_ _F. bancrofti._
_F. demarquayi._
_F. taniguchi._
_F. (?) conjunctivæ._
Group. _Agamofilaria_ -- _Ag. georgiana._
_Ag. palpebralis._
_Ag. oculi humani._
_Ag. labialis._
_F. (?) romanorum-
orientalis._
_F. (?) kilimaræ._
_F. (?) sp. ?_
(_Mikrofilaria_) _Mf. powelli._
_Mf. philippinensis._
_Setaria_ _S. equina._
_Loa_ _L. loa._
_Acanthocheilonema_ _Ac. perstans._
_Dirofilaria_ _Di. magalhãesi._
_Onchocercinæ_ _Onchocerca_ _O. volvulus._
_Trichinellidæ_ _Trichurinæ_ _Trichuris_ _T. trichiura._
_Trichinellinæ_ _Trichinella_ _T. spiralis._
_Dioctophymidæ_ -- _Dioctophyme_ _D. gigas._
_Strongylidæ_ _Metastrongylinæ_ _Metastrongylus_ _M. apri._
_Trichostrongylinæ_ _Trichostrongylus_ _T. instabilis._
_T. probolurus._
_T. vitrinus._
_Hæmonchus_ _H. contortus._
_Mecistocirrus_
(_Nematodirus_) _M. fordi._
_Ancylostominæ_
Group. _Œsophagostomeæ_ _Ternidens_ _T. deminutus._
_Œsophagostomum_ _Œ. brumpti._
_Œ. stephanostomum_
var. _thomasi_.
_Œ. apiostomum._
Group. _Ancylostomeæ_ _Ancylostoma_ _A. duodenale._
_A. ceylanicum._
_A. braziliense._
Group. _Bunostomeæ_ _Necator_ _N. americanus._
_N. exilidens._
Group. _Syngameæ_ _Syngamus_ _S. kingi.
Physalopteridæ_ -- _Physaloptera_ _P. caucasica._
_P. mordens._
_Ascaridæ_ _Ascarinæ_ _Ascaris_ _A. lumbricoides._
_A. sp._
_A. texana._
_A. maritima._
_Toxascaris_ _T. limbata._
_Belascaris_ _B. cati._
_B. marginata._
_Lagocheilascaris_ _L. minor._
_Oxyuridæ_ -- _Oxyuris_ _O. vermicularis._
_Mermithidæ_ -- _Mermis_ _M. hominis oris._
(_Agamomermis_) _Ag. restiformis._

Family. *Anguillulidæ.*

Genus. *Rhabditis*, Dujardin, 1845.

Buccal cavity elongated, with lips. Its chitinous wall uniformly
thick. Lateral lines absent. Males with bursa.

*Rhabditis pellio*, Schneider, 1866.

Syn.: _Pelodera pellio_, Schn., 1866; _Rhabditis genitalis_,
Scheiber, 1880; _Rhabditis pellio_, Schn., 1866.

Males 0·8 to 1·05 mm. in length; females, 0·9 to 1·3 mm. in length. The posterior extremity of the body of the male has a heart-shaped bursa, and seven to ten ribs on each side; the bursa may, however, be lacking. The spicules measure 0·027 to 0·033 mm. in length, but are never quite alike. The posterior extremity of the female is long and pointed; the vulva lies somewhat behind the middle of the body, the ovary is single, the eggs are oval, 60 µ by 35 µ.

This species was found in Stuhlweissenburg by Scheiber in the acid
urine (containing albumin, pus and blood) of a woman suffering from
pyelonephritis, pneumonia and acute intestinal catarrh; the observer
was able to convince himself that the Nematodes which were found
during the whole period of the illness lived in the vagina, and were
evacuated with the urine.

Oerley proved that this species had long been known; during its larval stage (_Anguillula mucronata_, Grube, 1849) it lives in earthworms; in its adult stage it lives in decomposing matter in the soil. By introducing individuals of this species into the vagina of mice, Oerley succeeded in obtaining infection and multiplication (facultative parasitism). These Nematodes must in some such way have got into the vagina of Scheiber’s patient.

Two other cases described by Baginsky and Peiper probably belonged to the same or a nearly related species.

*Rhabditis niellyi*, Blanchard, 1885.

Syn.: _Leptodera niellyi_, Blanchard, 1885.

In 1882 Nielly had a cabin-boy, aged 14, under observation in Brest. The lad had never left the neighbourhood of Brest, and had suffered from itching papules on the skin for five or six weeks; in the papules the observer found one or several rhabdites, measuring 0·33 mm. in length by 0·30 mm. in breadth. Their cuticle presented a delicate transverse striation; the intestine was the only internal organ recognizable, and it opened somewhat in front of the posterior extremity. Therefore, it must have belonged to the rhabditis-like larva of a Nematode, the adult stage of which is unknown.

The manner of infection was established almost certainly by a further
observation of Nielly’s: at the commencement of the illness small
Nematodes were found in the blood of the patient; later on, however,
they disappeared, neither were Nematodes found in the fæces, urine
or sputum. Therefore it must be concluded that the cabin-boy, who
was in the habit of drinking water from brooks, had thus ingested
embryo-containing eggs of a Nematode; the young hatched out in the
intestine, perforated it, reached the blood and then settled in the
skin; but, on the other hand, the entry may have been direct through
the skin.

In connection with the foregoing, reference should be made to a
communication by Whittles, insufficient from a zoological point of
view. In a case of hypertrophic gingivitis occurring in a female
patient, aged 19, who had never left Birmingham, he found Nematode
larvæ in the periosteum of the upper jaw, which was excised after
extraction of the right premolar; the genital rudiment could be
recognized in them. Similar larvæ were found in the same patient in
abscesses in various regions of the skin, and in the case of her
mother in the blood. The author considers that the infection took
place through a dog, and refers to the case of O’Neil (1875), who
found Filariæ in the skin (in the condition known as “craw-craw”),
referred by Manson to _Filaria perstans_. O’Neil’s case was quoted,
and attributed to _Filaria sanguinis hominis_. In conclusion, the
author states that he has repeatedly found Nematode larvæ in the
blood of persons who suffered from pruritus; in his opinion the
parasite had been imported through the agency of troops returned
from South Africa. Glatzel found true Filaria larvæ in a pustule of
a cutaneous eruption of the trunk and extremities in a patient at
Dar-es-Salam.

Skin diseases which are caused by young Nematodes are also observed
in dogs (Siedamgrotzky, Möller, J. G. Schneider, Künnemann),
foxes (Leuckart), and horses (Semmer). Zürn found young Nematodes
(_Anguillulidæ_) also in pig’s flesh. In Künnemann’s case it was
shown that the adult Rhabdites lived in the straw upon which the dog
lay.

*Rhabditis*, sp.

In the fluid obtained by lavage from the stomach of a female
patient, aged 16, suffering from ozæna, O. Frese found during two
consecutive months Rhabdites of various ages, 0·275 to 0·64 mm. in
length, the adults all with eggs; males were not found; transmission
into rabbit’s stomach failed, but they could be kept alive in much
diluted hydrochloric acid (2 : 1,000) for several weeks. Neither eggs
nor larvæ appeared in the fæces of the patient. The nature of the
infection, which was perhaps of unique occurrence, remained doubtful.

Genus. *Anguillula*, Ehrenberg, 1826.

Buccal cavity very small, without lips. Males without bursa, but with
a series of papillæ. Lateral lines absent.

*Anguillula aceti*, Müller, 1783.

Cuticle unstriped, body cylindrical, anterior end tapering but little, posterior end long, pointed. Male up to 1·45 mm. long, 0·024 to 0·028 mm. wide; two pre-anal papillæ, one post-anal; spicules equal, curved, 0·038 mm. long; gubernaculum present; testis extending in front of mid-line of body. Female up to 2·4 mm. long, 0·040 to 0·072 mm. wide; anterior uterus reaching to near the œsophagus, posterior to hind gut. Viviparous; embryos in both or only in one uterine horn, 0·22 mm. long, 0·012 mm. broad.

The species is a frequent inhabitant of vinegar (prepared by older
methods), and was once observed for some time by Stiles and Frankland
in the urine of a woman; the urine had an acid reaction, and once had
a distinct odour of vinegar. It was assumed that the patient, who
was hysterical and suffered from chronic nephritis, employed vaginal
douches with diluted vinegar, perhaps to deceive her physician or
to protect herself against conception. According to Ward, Billings
and Miller are said to have reported on two other cases. Ill-effects
which might be connected with the vinegar eel (_Anguillula aceti_)
were not present.

Genus. *Anguillulina*, Gervais and Beneden, 1859.

Syn.: _Tylenchus_, Bastian, 1864.

Characterized by the possession in the buccal cavity of a spine
knobbed posteriorly; bursa present; uterus asymmetrical. Numerous
species parasitic in plants.

*Anguillulina putrefaciens*, Kühn, 1879.

Syn.: _Tylenchus putrefaciens_, Kühn; _Trichina contorta_, Botkin,
1883.

In 1883 Botkin (_Pet. klin. Wochenschr_., 1883) found a small
Nematode, which was, however, entirely mistaken, in the material
vomited by a Russian; this was not a species of Trichinella, but an
_Anguillulina_ living in onions which had already, in 1879, been
described by Kühn as _Tylenchus putrefaciens_; the Nematodes got into
the stomach with the onions, causing nausea and vomiting.

Family. *Angiostomidæ*, Braun, 1895.

Genus. *Strongyloides*, Grassi, 1879.

Syn.: _Pseudorhabditis_, Perroncito, 1881; _Rhabdonema_, Leuckart,
1882, _p.p._

The genus is insufficiently defined. The parasitic form possesses a
simple mouth opening directly into the long cylindrical œsophagus
which occupies the anterior third of the body. The free-living forms
possess a small buccal cavity; the œsophagus is short, with a double
bulb, in the hinder one there is a *Y*-shaped chitinous valve; two
spicules of equal size.

*Strongyloides stercoralis*, Bavay, 1877.

Syn.: _Anguillula intestinalis_ et _stercoralis_, Bavay, 1877;
_Leptodera intestinalis_ et _stercoralis_, Cobb.; _Pseudorhabditis
stercoralis_, Perroncito, 1881; _Rhabdonema strongyloides_, Leuckart,
1883; _Strongyloides intestinalis_, Grassi, 1883; _Rhabdonema
intestinale_, Blanchard, 1886.

In 1876, a number of French soldiers returned to Toulon from
Cochin China suffering from severe diarrhœa. Dr. Normand, under
whose treatment they were, discovered a large number of Nematodes
in the evacuated fæces, and Bavay described them as _Anguillula
stercoralis_. Soon after Normand, at the _post-mortem_ of five
patients who had died of Cochin China diarrhœa, found numerous other
Nematodes in the intestine, from the stomach to the rectum, in the
bile-ducts and in the pancreas, and these he handed over to Bavay.
The latter diagnosed another species, and described them as _A.
intestinalis_. Both forms were then regarded as the cause of Cochin
China diarrhœa until, in 1882, Leuckart was able to demonstrate
that the two forms are only two succeeding generations of the same
species, of which the one (_A. intestinalis_) lives parasitically in
the intestine, whereas its young (_A. stercoralis_) attain the open,
where they come to maturity and propagate. The young of these again
live parasitically. There thus exists the same heterogony as was
discovered by Leuckart in _Angiostomum nigrovenosum_ of frogs, which
heterogony, indeed, according to v. Linstow, appertains to the entire
family of the _Angiostomidæ_.

(1) The parasitic generation (strongyloid or filariform ♀) is quite colourless and cannot be seen _in situ_ even with a lens. To detect them it is necessary to scrape the mucosa of the jejunum and examine the scrapings microscopically. It measures 2·2 mm. in length, and 34 µ to 70 µ in breadth; the cuticle is finely transversely striated; the mouth is surrounded by four lips; the œsophagus is almost cylindrical and a third the length of the entire body. The anus opens shortly in front of the pointed posterior extremity; the vulva is situated at junction of middle and posterior thirds of the body; the uterus has no special ovejector; the eggs measure 50 µ to 58 µ in length, and 30 µ to 34 µ in breadth, and lie in a chain one behind the other (fig. 270). As in the case of _Angiostomum nigrovenosum_, Leuckart considers this stage to be hermaphroditic, the testes degenerating after having functioned; other authors (Rovelli) regard it as a female reproducing by parthenogenesis.

(2) The free-living generation (♂ and ♀) has a smooth body, cylindrical, somewhat more slender at the anterior extremity and pointed at the tail end. The mouth has four indistinct lips; the œsophagus is short with a double (rhabditis-like) bulb; there is a *Y*-shaped valve in the posterior bulb; the anus opens in front of the tail end. The males measure 0·7 mm. in length, 0·035 mm. in breadth. Their posterior end is rolled up; the two brown spicules are small (38 µ) and much curved. There is also a gubernaculum. The females measure 1 mm. in length or a little over; 0·05 mm. in breadth. The tail end is straight and pointed; the vulva lies somewhat behind the middle of the body. The yellowish, thin-shelled ova measure 70 µ in length and 45 µ in breadth.

As Askanazy has shown, the parasitic form bores deeply into the mucous membrane of the intestine, and frequently into the epithelium of Lieberkühn’s glands, both for nourishment and oviposition. The eggs then develop in the intestinal wall. The eggs which are found in scrapings from the mucosa occur, at least in the case of Strongyloides of the sheep, in chains enclosed in a thin tube or sheath, the origin of which is doubtful; possibly it is the uterus. The eggs themselves are only rarely found in stools, _e.g._, after a strong purge. The larvæ, which are hatched out, and measure 0·2 to 0·25 mm. long by 0·016 mm. broad, again reach the lumen of the intestine,[299] and grow to double or three times that size, until they are passed out with the fæces. They already differ from the parent (♀) in the shape (rhabditiform) of the œsophagus. When the external temperature is sufficiently high (26° to 35° C.), they become sexually mature after moulting. In about thirty hours they are completely developed and copulate, now forming the free-living rhabditiform generation. At lower temperatures the larvæ only moult, but do not escape from the old cuticle and do not develop further. At a temperature of about 25° C. only some of the larvæ attain maturity.

[299] As a case published by Teissier shows, they may also abnormally appear in the blood (_Arch. méd. expér. et d’An. path._, 1895, vii, p. 675).

The females of the free-living generation (rhabditiform) deposit from thirty to forty eggs, which develop rapidly, sometimes even within the uterus in the case of old females. After the larvæ have emerged from the egg-shell, they measure 0·22 mm. in length, and possess the characteristics of the parents (rhabditiform larvæ). When they have grown to 0·55 mm. they moult, and while losing their own characteristics they acquire the characteristics of their parasitic grandparents (strongyloid or filariform). After about eight days the free-living adult generation in the cultures have disappeared, and all the rhabditiform larvæ have been transformed into strongyloid or filariform larvæ; they then die off unless they reach the intestine.

This cycle of development holds good for _Strongyloides stercoralis_ of tropical origin (Bavay, Leuckart, Leichtenstern, Zinn). In the European Strongyloides the free-living generation, as a rule, is absent (Grassi, Sonsino, Leichtenstern, Braun); the rhabditis-like larvæ evacuated with the fæces are transformed into the strongyloid or filariform type of larva (in cultures which are easily made) which will only become adult if introduced into man.

So that we have these two cycles: (_A_) (1) ♀ parasitic, (2) eggs, the rhabditiform larvæ in fæces, (3) free-living strongyloid or filariform larva, (4) ♀ parasitic. (_B_) (1) (2) (3) as before, then (4) adult ♀ and ♂, free living, (5) eggs, (6) rhabditiform larva, (7) strongyloid or filariform larva, (8) ♀ parasitic.

Infection of man results not only from direct entry into the stomach but also, according to van Durme and Looss, through the skin.

_Occurrence in Man._--As already mentioned, _Strongyloides
stercoralis_ was first observed in persons suffering from so-called
Cochin China diarrhœa. From the enormous numbers of parasites
evacuated with the fæces, the cause of the disease was apparently
evident. It appeared, however, that only some of the soldiers
returning from Cochin China and Martinique, and suffering from
diarrhœa, harboured Strongyloides (Chauvin). Breton made the same
observations in Cochin China and found that only 10·4 per cent. of
cases of chronic dysentery, and 8·8 per cent. of chronic diarrhœa,
show Strongyloides. Normand, moreover, found that only a few of the
Europeans residing in Cochin China are exempt from _S. intestinalis_,
yet the people exhibit no intestinal symptoms; if, however, from any
cause a catarrhal condition of the intestine supervenes the condition
is changed, the parasites appear in larger numbers, and the disorder
is considerably intensified.

_S. intestinalis_, besides being present in the Indo-China region,
also occurs in the Antilles, in Brazil, Africa, and Europe; in 1878
it was discovered in Italy by Grassi and C. and E. Parona; in 1880 it
was also found in the labourers working at the St. Gothard tunnel. It
was imported into Germany, Belgium, and the Netherlands by Italian
labourers. One sporadic case has been observed in East Prussia, and
the worm has also been reported from Siberia.

In mammals the following species are found: _Probstmayria_
(_Strongyloides_) _vivipara_, Ransom, 1907, in _Equus caballus_;
_Strongyloides fülleborni_, v. Linst., in _Anthropopithecus
troglodytes_ and _Cynocephalus babuin_.

Their development is, so far as is known, the same as that of
_Strongyloides stercoralis_ (v. Linstow, _Centralbl. f. Bakt., Path.
u. Infektionsk._, 1905, Orig. xxxviii, p. 532).

Family. *Gnathostomidæ.*

Genus. *Gnathostoma*, Owen, 1836.

Syn.: _Cheiracanthus_, Diesing, 1839.

Easily recognizable by the numerous spines which cover the entire
body or only the anterior extremity, and terminate in several points;
head globular and beset with bristles; mouth with two lips; two
spicules; vulva situated behind the middle of the body.

*Gnathostoma siamense*, Levinsen, 1889.

Syn.: _Cheiracanthus siamense_, Lev., 1889.

Female measures 9 mm. in length, 1 mm. in breadth. There are eight rows of simple spines on the head; the armature of spines extends over the anterior third of the body only; each spine on the anterior region of the body spreads into three points, of which the middle one is the longest; the posterior spines are simple; they gradually become smaller and then disappear entirely. The vulva is situated behind the middle of the body.

_Male._--10·5 mm. long by 0·6 mm. broad. Head terminates in a globular swelling with two large lips. Neck 3 mm. broad. In front of neck eight rows of simple spines directed backwards. Anterior half of body with cuticular laminæ, posterior unarmed. Two pre-anal and two post-anal papillæ. Bursa wanting.

Spicules 1·1 and 0·4 mm. respectively.

Leiper considers _Gnathostoma siamense_ to be identical with _Gnathostoma spinigerum_.

The single specimen described by Levinsen was found by Deuntzer in
Bangkok (Siam), and was obtained from a young Siamese woman who
suffered from a small tumour of the breast which had developed in the
course of a few days. After the disappearance of the tumour, nodules
the size of beans were found in the skin; out of one of these the
worm was obtained. The same observer saw this affection in two other
persons.

A closely related species, _Gnathostoma spinigerum_, Ow., lives in
the stomach of wild cat (_Felis catus_), puma (_Felis concolor_),
tiger (_Felis tigris_), and domestic cat (India); another species,
_Gnathostoma hispidum_, Fedsch., 1839, in the stomach of pigs in
Turkestan, Annam, Hungary, Congo, and by Collin in the stomach of an
ox (Berlin).

_Gnathostoma_ sp. in pariah dogs, Calcutta. _Gnathostoma_ sp. in
monkeys, French Guiana. They produce large fibrous thickenings in the
stomach wall.

*Gnathostoma spinigerum*, Owen, 1836.

Cuticle of bulb with eight rows of chitinous laminæ with their posterior edges notched into spines. The laminæ on the anterior portion of the body are similar trident laminæ. In the middle of the body, the laminæ are simple and conical, cuticle posteriorly is unarmed. Mouth with two fleshy lips.

Male 5 mm. long by 0·5 mm. broad; tail spiral, four pairs of papillæ.

Female about twice as long; tail straight, trilobed.

Family. *Dracunculidæ*, Leiper, 1912.

Genus. *Dracunculus*, Kniphoff, 1759.

Anterior end rounded with a cuticular thickening or shield. Mouth triangular with two lips. Alimentary canal atrophied.

*Dracunculus medinensis*, Velsch, 1674.

Syn.: _Vena medinensis_, Velsch, 1674; _Dracunculus persarum_,
Kämpfer, 1694; _Gordius medinensis_, Linné, 1758; _Filaria
dracunculus_, Bremser, 1819; _Filaria æthiopica_, Valenciennes, 1856;
_Dracunculus medinensis_, Cobbold, 1864; _Guinea worm_, _Medina worm_.

The females attain a length of 50 to 80 cm., or even more, and average 1·5 to 1·7 mm. in diameter. They are whitish or yellowish in colour. The anterior extremity is roundish and bears a cuticular thickening or shield. The triangular mouth opening is surrounded by two projections or lips, behind which on the shield there are two lateral and four sub-median papillæ; the posterior end terminates in a spine, ventrally directed, and about 1 mm. in length; the alimentary canal below the œsophagus is atrophied, but not entirely obliterated; anus absent; the lateral lines are very flat. The greater part of the body is occupied by the long uterus, in which a great number of young larvæ are always found. The ovaries probably lie at the ends of the uterus; the vulva lies just behind the cephalic shield. During parturition the uterus is prolapsed through this opening.

The male is almost unknown. Leiper in an experimentally infected monkey found two males 22 mm. long, one from the psoas muscle, the other from the connective tissue behind the œsophagus.

_Occurrence._--_Filaria medinensis_ has been known since the most
remote period. The “fiery serpents” that molested the Israelites by
the Red Sea, and which Moses mentioned, were probably filariæ. The
term Δρακὁντιον occurs in Agatharchides (140 B.C.). Galen called
the disorder dracontiasis; the Arabian authors were well acquainted
with the worm. It is found not only in Medina or Arabia, but also
in Persia, Turkestan, Hindustan. The Guinea worm is also widely
distributed in Africa, on the coasts as well as in the interior. It
occurs in the Fiji Islands. It was carried to South America by negro
slaves, but is said at the present time to exist in only quite a
few places (British Guiana, Brazil [Bahia]); it is also observed in
mammals (ox, horse, dog, leopard, jackal [_Canis lapuster_], etc.).

_Dracunculus medinensis_ in its adult stage lives in superficial ulcers on the body surface; it is seen most frequently on the lower extremities, more especially in the region of the ankle, but it also occurs in other parts of the body--on the trunk, scrotum, perineum, on the upper extremities, and in the eyelids and tongue. Sometimes there is only one ulcer and one worm, but more commonly several. It attacks man without distinction of race, age or sex. It is observed most frequently during the months of June to August.

_Life history._[300]--When about a year old the worm seeks the surface of the body and produces there a thickening as big as a florin. Over this a vesicle forms which eventually ruptures, and at the bottom of the ulcer can be seen a hole from which a part of the worm may project. On bathing the sides of the ulcer with water, a drop of fluid, at first clear then milky, exudes. This contains numerous larvæ. In other cases a thin tube an inch long is prolapsed (through the vulva). This is probably the uterus, but the mechanism of parturition is not clearly known. It lasts for about a fortnight. An abundant supply of larvæ can be got by placing wet compresses on a _fresh_ ulcer. In a few hours a mass of larvæ is obtained.

[300] The larvæ resemble those of _Cucullanus elegans_ parasitic in the perch (_Perca fluviatilis_). The larvæ of this species develop in Cyclops sp. Fedschenko in 1870, at Leuckart’s suggestion, succeeded in observing the invasion of Cyclops by Guinea worm larvae. They penetrate not _per os_ but through the exoskeleton. Newly hatched larvæ (in bananas) will cause infection of monkeys.

The larvæ are 500 µ to 750 µ by 15 µ to 25 µ, with a long slender tail about one-third of the total length. The cuticle is transversely striated. The body is flattened. They possess an œsophagus and gut. At the anus there are apparently glandular structures.

The larvæ live and move actively in water for about two days, the majority dying on the third (Leiper). If a number of Cyclops sp. have been collected and isolated in clean water, and the larvæ are now added, the further development can be traced.

The larvæ enter the Cyclops, according to most authorities, by penetrating the exoskeleton, but according to Leiper this is impossible; they must enter by the mouth and penetrate the gut in order to reach the body cavity. In eight days moult 1 takes place, the striated cuticle being cast off. In ten days moult 2 takes place. In five weeks the larva is mature. If now the infected Cyclops is placed in 0·2 per cent. HCl solution the Cyclops is killed immediately, but the larvæ are stirred into activity, escape from the body, and swim about in the acid. This suggests that infection in nature probably takes place by the swallowing of infected Cyclops; Leiper, by feeding Cyclops containing mature larvæ to a monkey, found in it, _post mortem_ six months later, two immature females 30 cm. long and two males 22 mm. long.

In certain areas the new cases occur principally in June. Five weeks later the larvæ will become mature in Cyclops, so that infection of Cyclops is taking place in July or August, and from then to June about ten months elapse, giving the period of development in man.

_Pathology._--The initial induration is accompanied by itching. Urticarial eruptions are described in Dahomey and Mauretania accompanied by fever, rigors, blood-shot conjunctiva, and prostration resembling fungus poisoning. Symptoms last for one to two days, later the worms appear on the surface.

If the worm is ruptured in an attempt to extract it, disastrous results may occur through the escape of the larvæ into the tissues: fever, inflammation, abscess, sloughing, ankylosis, even death from sepsis. Eosinophilia is often marked, 11 to 13 or even 50 per cent.

_Extraction._--(1) The native method consists in rolling the worm round a stick; 1 in. to 2 in. are extracted each day, the process taking about a fortnight; (2) Emily used injections of 1 in 1,000 sublimate into the swelling or into the worm itself fixed by a ligature. (3) Béclère chloroforms the worm; (4) the worm can be more easily removed when all the embryos have been deposited (two to three weeks).

_Cyclopidæ._--Cephalothorax ovate, clearly separated from abdomen. Anterior antennæ of female when bent back scarcely ever stretch beyond the cephalothorax. The second antennæ are unbranched. First four pairs of feet two-branched, outer branches three-jointed. The fifth pair of limbs are rudimentary alike in both sexes, usually one-jointed. There is no heart. The female has two egg sacs containing about fifty eggs.

Genus. *Cyclops*, Müller, 1776.

Mandible palp rudimentary, reduced to a tubercle bearing two branchial filaments. Maxillary palp rudimentary (obsolete). Lower foot-jaw non-prehensile. Head ankylosed to first thoracic segment.

Family. *Filariidæ.*

Sub-family. *Filariinæ.*

The residue after exclusion of the _Arduenninæ_ and _Onchocercinæ_.

Genus. *Filaria*, O. Fr. Müller, 1787.

Very long, slender Nematodes, without excretory vessels or excretory pore, the males of which are usually considerably smaller than the females. Mouth round, without lips, unarmed. The lateral lines occupy one-sixth of the circumference of body. The tails of the males are bent or spirally rolled, and bear little wing-like appendages. The two spicules are unequal; almost always there are four pre-anal papillæ, but the number of post-anal papillæ varies. The vulva is always situated at the anterior extremity. Parasitic chiefly in the serous cavities and in the subcutaneous connective tissue. Insufficiently defined.

*Filaria bancrofti*, Cobbold, 1877.

Syn.: _Trichina cystica_, Salisbury,[301] 1868 (_nec Filaria
cystica_, Rud., 1819); _Filaria sanguinis hominis_, Lewis, 1872;
_Filaria sanguinis hominis ægyptiaca_, Sonsino, 1875; _Filaria
wüchereri_, da Silva Lima; _Filaria sanguinis hominum_, Hall,
1885; _Filaria sanguinis hominis nocturna_, Manson, 1891; _Filaria
nocturna_, Manson, 1891.

[301] C. W. Stiles (“American Medicine,” 1905, ix, p. 682) is of the opinion that Salisbury’s _Trichina cystica_ is identical with _Oxyuris vermicularis_.

These parasites of man were for a long time only known in their
larval stage. They were discovered in 1863 in Paris by Demarquay, in
the hydrocele fluid of a Havanese emptied by puncture; they were next
observed by Wücherer, in Bahia, in the urine of twenty-eight cases
of tropical chyluria; they were likewise observed in North America
by Salisbury, who gave them the name of _Trichina cystica_. The next
discoveries (in Calcutta, Guadeloupe, and Port Natal) related to
chyluria patients, until Lewis discovered the larvæ in the blood of
man (India), and found they were almost always present in persons
suffering from chyluria, elephantiasis, and lymphatic enlargements;
he also, in exceptional cases, found them in apparently healthy
persons (_Filaria sanguinis hominis_). Lewis and Manson studied the
disease and the filariæ of the blood very minutely, and became aware
that the filariæ were sucked up by mosquitoes with the blood. Manson
described the metamorphoses that take place within the body of the
mosquito. The adult female was discovered in Queensland by Bancroft,
and soon after Lewis found it in Calcutta; it was described by
Cobbold as _F. bancrofti_. The male was first seen by Bourne in 1888.

Head bougie-like, _i.e._, separated by a narrowing from the neck, having two rows of minute papillæ. Cuticle has extremely fine striations.

_Female._--50 to 65 mm. long by 1·5 to 2 mm. broad. Vulva 0·4 to 0·7 mm. behind the head. Anus about 1/4 mm. from the tip of the tail (vulva 1 to 1·3 mm. from head, and anus 0·17 to 28 mm. from tail according to other authors). The vagina is a muscular tube forming three bold loops, and has terminally a pyriform enlargement. Uterus double (or single). Ovoviviparous.

_Male._--25 to 30 mm. long by 0·1 mm. thick (40 by 0·1 mm. according to various authors). Probably two pairs of pre-anal papillæ, eight pairs of peri-anal, two pairs of post-anal papillæ, and one pair terminal. Tail curved. Two spicules, 0·2 and 0·6 mm. respectively, and a cup-like gubernaculum. The long spicule is cylindrical, expanded proximally and tapering distally to a filament with wings. At the tip it is spoon-like. The short spicule is of the same diameter throughout. It is gutter-like, coarsely marked. Testis uncoiled, terminating in a snowdrop-like process (Leiper).

_Eggs._--40 µ by 25 µ. They do not appear to possess a true shell, but only an embryonal or vitelline membrane secreted by the ovum.

_Embryos._--In the posterior part of the uterus eggs occur, in the anterior part embryos; the larvæ at birth measure 127 µ to 200 µ by 8µ to 10 µ. In the blood they measure in the fresh 260 µ by 7·5 µ to 8 µ. In stained films, owing to shrinkage, there is great variation in size, from 154 µ to 311 µ. Probably 260 µ to 285 µ is the average in stained films.

_Geographical Distribution._--Europe: Two cases recorded, one from near Barcelona. The patient suffered from hæmato-chyluria and enlarged scrotum with mikrofilariæ in the blood. A second case from Siena. Africa: The filarial index has not been estimated for various parts. In Nigeria it is about 10 per cent.

_Habitat._--Lymphatic glands: _e.g._, inguinal, femoral, iliac, lumbar, mesenteric, bronchial, superficial cervical, epitrochlear.

Lymphatic vessels: _e.g._, those draining into the receptaculum chyli of the spermatic cord, in the thoracic duct and in various different parts.

Organs, etc.: Testis, epididymis, spermatic cord, tunica vaginalis, mammary cyst, and in abscesses.

They may occur in masses, but usually only a few (one to eight). Females are commoner than males. Dead and calcified worms are common in the various sites.

_Distribution of Larvæ in Body._--These are by no means uniformly distributed, but occur in greater number in the capillaries of the lungs. Besides the lungs they occur in the capillaries of other organs, as the following data of Rodenwaldt show:--

Mikrofilariæ Mikrofilariæ
Lungs 134,821† Spleen 1,666
Liver 4,884 Brain 3,833
Kidneys 15,253 Glands 0
{Glomeruli 8,008 Marrow 0
{Parenchyma 7,245 Blood 3,000

† These figures refer to 1 c.c. of each organ, and were estimated by
cutting sections of definite thickness (30 µ to 40 µ) and counting
the filariæ in a definite area of section, _e.g._, 1/4 cm.^2 The
organs before removal from the body have their vessels tied, and are
then fixed in hot alcohol.

The following data of Rodenwaldt refer to the larvæ of _Filaria immitis_ in the dog. They are commoner in organs than in vessels, and especially in the _capillaries_ of the organs, but in the lungs they appear to be equally distributed in capillaries, arteries and veins.

The length of life of larvæ is unknown, but they appear to be destroyed in the kidneys, as dead calcified specimens are fairly numerous in the capillaries of the vasa recta of the medullary substance.

Kidneys: mainly in the glomerular capillaries and those of the vasa recta.

Liver: in the capillaries of the portal system, especially in those between the interlobular and the central intralobular veins.

_Periodicity of Larvæ._[302]--Roughly speaking, the larvæ of _Filaria bancrofti_ are found in the peripheral blood only during the night, disappearing (but not entirely) during the daytime. Their periodicity and that of _Loa loa_ larvæ is shown by the table on p. 394, based on that of Smith and Rivas (_Amer. Journ. Trop. Dis. and Prev. Med._, 1914, vol. iii, p. 361).

[302] For determining periodicity measured quantities of blood, _e.g._., 20 mm.^3, should be used. A thick film is made of the whole quantity. The numbers present in this quantity may vary from three or four to 300 or 400.

It was discovered by Mackenzie that this periodicity could be reversed by making the patient sleep during the daytime, showing that the phenomenon was in some way dependent on sleep or its attendant phenomena. Rodenwaldt gives the following explanation of the phenomenon of periodicity:--

Mikrofilariæ come to rest in capillaries. After passing up the thoracic duct they would reach the capillaries of the lungs by the superior vena cava. Here they occur in immense numbers. In the case of _Loa loa_ larvæ (which have a diurnal periodicity) some of these are forced out by the increased force and rapidity of the pulmonary circulation during the day, but are able to rest (owing to their sticky sheath?) in the peripheral capillaries on their way to the capillaries of the organs. During the night the force of the current through the lungs is relaxed and consequently they are able to remain in the pulmonary capillaries and do not appear in the capillaries of the systemic circulation. If it is true that the periodicity of _Loa loa_ cannot be reversed by changing the hours of sleep, then the explanation is incomplete. In the case of the larvæ of _Filaria bancrofti_ (which have a nocturnal periodicity), in order to apply the same explanation we must further assume that the mikrofilariæ have less power of resisting the force of the capillary current (_i.e._, are less sticky). They are washed out of the pulmonary capillaries by day and by night, but it is only at night, when the blood stream in systemic capillaries is less rapid, that they are able to rest there. In the daytime they are washed on until they reach the capillaries of the organs (possibly again the lungs). The reversal of the periodicity by sleeping during the daytime admits of a similar explanation. If this explanation be true, then a prolongation of the day conditions, _e.g._, by continued exercise, should result in still keeping the larvæ out of the circulation, but this does not appear to be the case.

--------+----------+----------+----------+----------+----------+----------
| Larvæ of | Average | CASE 1. | Average | CASE 2. | Average
| _L.loa_ | 132. | _F. | 1,000 | _F. | 1,570
| in equal |Deviations|bancrofti_| (about). |bancrofti_| (about).
|quantities| from | larvæ |Deviations| larvæ |Deviations
| of blood | average |in 1 c.c. | from |in 1 c.c. | from
| | | of blood | average | of blood | average
--------+----------+----------+----------+----------+----------+----------
2 a.m. | 9 | - 123 | 3,500 | + 2,500 | 6,500 | + 3,930
4 a.m. | 11 | - 121 | 3,200 | + 2,200 | 5,200 | + 3,630
6 a.m. | 41 | - 91 | 2,800 | + 1,800 | 2,000 | + 430
8 a.m. | 168 | + 36 | 900 | - 100 | 1,100 | - 470
10 a.m. | 298 | + 166 | 210 | - 790 | 350 | - 1,220
12 noon | 531 | + 389 | 30 | - 970 | 50 | - 1,520
2 p.m. | 252 | + 120 | 20 | - 980 | 40 | - 1,530
4 p.m. | 146 | + 14 | 10 | - 990 | 30 | - 1,540
6 p.m. | 91 | - 41 | 40 | - 960 | 40 | - 1,530
8 p.m. | 23 | - 99 | 60 | - 940 | 100 | - 1,470
10 p.m. | 5 | - 127 | 600 | - 400 | 800 | - 770
12 mid- | 5 | - 127 | 750 | - 250 | 2,600 | + 1,030
night| | | | | |
--------+----------+----------+----------+----------+----------+----------
Total | 1,580 | -- | 12,120 | -- | 18,810 | --
--------+----------+----------+----------+----------+----------+----------

In certain countries, _e.g._, Fiji, Samoa, Philippines, West Africa, larvæ, apparently those of _Filaria bancrofti_, show no periodicity. In Fiji the usual intermediate host is _Stegomyia pseudoscutellaris_, a day-biting mosquito, so that possibly, as Bahr suggests, the mikrofilariæ have partly adapted themselves to the habits of their intermediate host, as the nocturnal mikrofilariæ are adapted for transmission by a nocturnal feeding mosquito, _e.g._, _Culex fatigans_, but how this could come about is a mystery. It is not certain in all cases whether the non-periodic mikrofilariæ really belong to _Filaria bancrofti_; some may be _L. loa_ larvæ, or possibly unknown larvæ. An exact morphological description of these larvæ is therefore always necessary.

_Preservation of Living Larvæ._--Blood from the vein (or finger puncture) is shaken up with twenty times its volume of sterile 0·9 per cent. salt solution, and kept in an ice cupboard (Fülleborn).

_Concentration of Larvæ._--(_a_) The above mixture is hæmolysed with water and then sufficient salt solution added to make up to 0·9 per cent. The solution is allowed to stand or can be centrifugalized. (_b_) The blood is mixed with sodium citrate and centrifugalized; the larvæ are found in the leucocytic layer (Bahr). (_c_) Allow blood to clot in a small tube; the larvæ appear on the surface of the clot and are so got in pure serum. A drop of blood may also be allowed to clot on the slide; the larvæ are found in the clear areas of serum. (_d_) Hæmolyse blood with water or acetic acid. Centrifugalize, make smears from, or examine the sediment.

_Removal of Red Corpuscles._--The blood film is allowed to stand for some minutes in a moist atmosphere. The staining solution is sucked through with blotting paper: the larvæ stick to the slide, while the corpuscles are washed out.

_Morphology of Larvæ._--Wet staining: Azur II one part, 0·9 per cent., salt solution 3,000, or very dilute Giemsa or ripened methylene blue or neutral red solutions. Place a drop on the slide and add a drop of blood to this. The larvæ remain alive for one or more days; it sometimes takes twenty-four hours to stain some particular structure. Differentiation by drawing through weak eosin solution is often useful. This method is the best for finest details. The excretory pore, anal pore, excretory cell, and chief “genital” cell stain first, then the matrix cells and finally the column of nuclei.

Wet fixation and staining: The blood is spread on a large cover-glass--floated on the surface of 70 per cent. alcohol heated to about 70° C. Wash in water, (1) overstain with 1 in 1,000 azur II solution, warming slightly; (2) differentiate with (_a_) absolute alcohol (containing, if necessary, a trace of HCl), or (_b_) with absolute alcohol 96 per cent. ninety parts, anilin oil ten parts; (3) clear in origanum, bergamot or cajeput oil; (4) mount in balsam. Or stain with hæmatoxylin, _e.g._, Mayer’s glycerine alumhæmatein, heating till slightly steaming. Differentiate with acid (2 per cent. HCl) alcohol if overstained. Clear and mount as above.

Dry fixation and staining: (1) With azur II as above, or (2) with hæmatein (warm). Examine the dried films in the usual way without a cover-glass. The azur stains the excretory and genital cells clearly.

Thick films: (1) The blood is smeared out fairly thickly over an area as big as a sixpence.

(2) Dry _quickly_ to prevent shrinking, using carefully a spirit lamp in a moist climate.

(3) Place films downwards in water for a few minutes.

(4) Fix in alcohol.

(5) Stain with azur II, 1 in 1,000. Differentiate as above. Examine as a dry film. This method suffices for showing the excretory cell and the G1 cell; or

(6) Stain with hæmatein (slightly steaming), especially for the column of nuclei and the sheath. The fixation in alcohol in this case may be omitted.

(7) The removal of the hæmoglobin and the fixation may be combined by using Ruge’s mixture (formalin 2 per cent., containing 1 per cent. acetic acid) or acetic alcohol (glacial acetic 1, alcohol 3).[303]

[303] [Acetic alcohol does well for detecting crescents in thick films of malaria blood.--J. W. W. S.]

_Structure of Larvæ._--(1) Subcuticular cells: By vital staining, at intervals underneath the cuticle are seen a series of spindle-shaped cells--the _subcuticular matrix cells_ of Rodenwaldt, the _muscle cells_ of Fülleborn. There are thirty or forty or more of these.

(2) Nerve ring: Appears as a break in the nuclear column about 20 per cent. of total length from the head.

(3) Excretory system: Consists of a lateral spherical hollow excretory pore which shows a radial striation. Connected with the pore is an excretory cell which appears to be canalized. _Excretory pore_, 29·6 per cent. of length from head. _Excretory cell_, 30·6 per cent. of length from head.

(4) “Genital” cells and anal pore: Consists of a pore opening ventrally on a very fine papilla with which are connected four other cells in series, the chief “genital” cell (G1) being some distance from the three others, which lie close to the pore. G1, 70·6 per cent., anal pore, 82·4 per cent. of length from head.

(5) Internal body, viscus, or reserve material: Best shown by vital staining with neutral red. This is a granular strand-like body extending from 52·7 per cent. to 65 per cent. of length from head.

(6) Tail end: (i) Rod-like structures resembling those in the head, 90 per cent. of length. (ii) The column of nuclei extends to 95 per cent. of length, so that the terminal portion is free from nuclei.

(7) Mouth: Terminal according to some authors, lateral according to others. Some describe a fang on the head, others not. By vital staining and eosin differentiation two rod-like structures with mushroom-like caps can be seen behind the head.

(8) Cuticle: Transversely striated. There is a longitudinal break in the striation on each side corresponding to the lateral lines. The striation is best shown by vital staining with azur II and eosin differentiation.

(9) Column of nuclei: These nuclei of the gut cells form the main feature in ordinary dry films stained with hæmatoxylin. They are separated by a space from the subcuticular cells.

DISTINCTION BETWEEN _Mikrofilaria bancrofti_ AND _Mikroloa loa_.

_Dry Films, Hæmatoxylin Staining_:--

_Mf. bancrofti._ _Ml. loa._

(1) In graceful curves (but only (1) Kinked.
if quickly dried).
(2) Tip of tail free from nuclei. (2) Nuclei extend to tip.
(3) Column of nuclei separated by (3) Not so distinctly.
a space from the cuticle.

_Azur Staining_:--

(4) G1 cell small, easily overlooked. (4) G1 cell large, stains
deep blue, cell
protoplasm = twice
width of larva,
easily seen.
(5) Excretory cell close to excretory (5) Excretory cell farther
pore, 2 per cent. of length. from pore, 4 per
cent. of length.

_Vital Staining with Neutral Red_:--

(6) Internal body or reserve material (6) Not shown.
clearly shown.

_Life History._--In the stomach of the mosquito the larvæ cast their sheath in the thickened blood in one to two hours. In twenty-four hours the majority have reached the thoracic muscles, where development proceeds. They are at first immobile and of a “sausage” form (110µ by 13 µ), with a short spiky tail. In three to five days the œsophagus is formed, the larva now being 0·5 mm. long. The larva appears to moult at this time. After the gut is formed papillæ, three or four in number, appear at the tail end. In two to three weeks the larvæ are 1·5 mm. long. They now leave the thorax and reach the labium, but they may be found in various parts of the body, _e.g._, the legs. They bore through Dutton’s membrane and so arrive on the surface of the skin, which they rapidly enter. Their development in man is unknown, but it may be very long, as children are not infected till 4 to 5, or even 10 years old, but this may be due to unknown causes.

Development takes place in numerous mosquitoes. Anophelines: _Myzomyia rossii_, _Pyretophorus costalis_, _Myzorhynchus sinensis_, _Myzorhynchus barbirostris_, _Myzorhynchus peditæniatus_.

Culicines: _Culex pipiens_, _Culex fatigans_, _Culex skusei_, _Culex gelidus_, _Culex sitiens_, _Culex albopictus_, _Stegomyia fasciata_, _Stegomyia pseudoscutellaris_, _Stegomyia gracilis_, _Stegomyia perplexa_, _Mansonioides uniformis_, _Mansonioides annulipes_, _Scutomyia albolineata_, _Tæniorhynchus domesticus_.

Partial development takes place in other species.

_Pathology._--Among the conditions which _Filaria bancrofti_ is believed to produce are lymphangitis, varicose glands, especially inguinal and epitrochlear, chyluria, chylocele, lymph scrotum, orchitis, abscess, and elephantiasis. The evidence that these so-called “filarial diseases” are produced by _F. bancrofti_ is (1) geographical and statistical; (2) pathological. Bahr has contributed evidence of the former kind from his researches in Fiji, on which we may base the following statements:--

(1) The prevalence of filarial diseases is proportional to the prevalence of _Mikrofilaria bancrofti_ in the blood. Thus in four villages examined by him he got the following figures:--

Village A Village B Village C Village D
per cent. per cent. per cent. per cent.
_Mf. bancrofti_ 12·5 25 31 33
Filarial diseases 29 39 58 34
Total population 168 114 425 222

(2) Out of 257 people with _Mf. bancrofti_ in the blood, 153 were suffering from filarial diseases, _i.e._, 59 per cent.

(3) Whereas of 672 people without _Mf. bancrofti_ in the blood, only 263 were suffering from filarial diseases, _i.e._, 37·6 per cent.

(4) Again out of 416 people suffering from filarial disease, 153 showed _Mf. bancrofti_ in their blood, _i.e._, 36·7 per cent.

It is generally assumed that all people suffering from filarial disease show at some (presumably early) stage larvæ in the blood; but we do not consider that this must necessarily be so. It appears to us quite possible that living adult filariæ may be present in the body, producing disease, without their larvæ appearing in the blood. The absence of larvæ from the blood in 63·3 per cent. of persons suffering from filarial disease is, however, generally explained otherwise. The adults which occur in enlarged glands, etc., get eventually destroyed by inflammatory reaction, so that larvæ are no longer being produced, while the enlarged gland, etc., which the adults have produced remains. This explanation assumes that the larvæ of the original worm die in the circulation or elsewhere, _e.g._, kidney, but we have no evidence as to the duration of life of larvæ in the human body; but also it assumes that a person cannot be reinfected with filaria, for otherwise there is no reason why the diseased should not be infected in the same proportion as the non-diseased. But assuming the explanation to be true, it would explain why a diseased population show larvæ in only about one-third of the cases. It must be borne in mind also that the figures are rather small.

_Pathology._--In order to explain the effects which do or may be expected to occur from obstruction of lymphatics, it is necessary to have an accurate knowledge of the distribution and connections of lymphatic vessels (and glands) and the anastomoses of these vessels. We can only briefly summarize our knowledge here.

We should recall also that considerable destruction or obstruction of lymphatics or glands may occur without necessarily producing any lymphatic obstruction, at least, of a permanent nature, _e.g._, when a mass of lymphatic glands is destroyed by a bubo in the groin or, again, when a carcinomatous mass of glands is removed from the axilla. Again, to take the case of chyluria--where it is generally assumed that obstruction must occur higher up than the point at which the intestinal lacteals enter the juxta-aortic glands--this disease may occur, _e.g._, in temperate regions, quite apart from such obstruction. It is true that some of these cases of chyluria are not cases of chyle in the urine, but, as little or no fat is present, lymphuria. These do not require the above assumption, but seeing that true chyluria may apparently occur without such obstruction, we should be cautious about explaining this and other symptoms on the basis of obstructions which theory may demand, for only too often there are no _post-mortem_ facts at our disposal.

Lymphangitis: What this is due to is unknown. There is no actual evidence of the occurrence of adults in the inflamed vessel. Complete disappearance, not to reappear, of (non-periodic) mikrofilariæ from the blood has been shown by Bahr and others to occur within twenty-four hours after an attack of lymphangitis, orchitis adenitis or simply a high temperature. This mysterious phenomenon requires explanation. If the mikrofilariæ were being killed by the attack, their dead bodies should still be found in the blood; or if the adults were being killed, for all we know to the contrary, the larvæ might well survive. We consider there is no evidence that either are affected, but that for some reason, as little understood as in periodicity, the larvæ now remain in the organs.

Abscess: In Fiji, by Bahr, they have been found in the substance of various muscles, _e.g._, quadriceps extensor, latissimus dorsi, serratus magnus, in the popliteal space, groin, axilla, and over the internal condyle of the humerus, and in the upper extremity they are frequently infected with cocci. They not infrequently contain fragments of dead adult filariæ. Their mode of origin is not clear. They form nearly 30 per cent. of cases of filariasis in Fiji. Of 95 cases, 41 showed mikrofilariæ in blood, 54 did not.

Hydrocele and enlarged testis: In Fiji they form about 10 per cent. (36 out of 343) of cases of filariasis. The fluid is usually sterile; mikrofilariæ were present in the fluid in 1 out of 11 cases. In the wall numerous calcified adult filariæ may be found. The walls consist chiefly of hypertrophied muscle with fibrous tissue, dilated blood-vessels and lymphatics, the lining epithelium of which appears to be absent; of 38 cases 14 had mikrofilariæ in the blood, 24 had not. Most of the cases are associated with elephantiasis of the scrotum (11 out of 12 cases).

Enlarged glands form over 40 per cent. (153 out of 343) of cases of filariasis, so that they are the commonest expression of filariasis met with in Fiji. The glands are enlarged, fibrotic, and the trabeculæ are thickened. The lymphatics are thickened or represented merely by fibrous tissue. The gland also shows dilated blood-vessels and numerous spaces filled with lymph. Giant-cells are common in those glands which contain remnants of filariæ. Masses of lymphocytes enclosed by inflammatory or fibrous tissue are common. Eosinophile cells are also extremely common, not only in the fibrous tissue of the glands, but in other inflammatory or fibrotic conditions: in other organs living or calcified filariæ are “usually” present. Only about 33 per cent. show mikrofilariæ in the blood. The epitrochlear gland is frequently enlarged in Fiji.

Breinl has examined enlarged glands and finds loose vascular fibrous tissue with lymphocytic invasion. In parts, the lymphocytes collect into areas 200 µ to 800 µ in diameter. The lymph tissue surrounding the spermatic cord showed abundance of vessels--(1) large, (2) small. The large had thick walls and wide lumina. In other cases the lumina were nearly filled by a thrombus of newly formed, fine, loose connective tissue.

Varicose glands: In about 7 per cent. (24 out of 343 cases) of filariasis, mikrofilariæ are found in the blood in 50 per cent. (12 out of 24).

_Elephantiasis._--Elephantiasis scroti is associated with hydrocele in 50 per cent. of cases (12 out of 23); in 65 per cent. of cases (15 out of 23) there are associated enlarged glands in one or both groins, though also hydrocele and enlarged glands occur without elephantiasis scroti. In 13 out of 27, _i.e._, about 50 per cent., cases of elephantiasis in various regions, no associated enlargement of glands is found. Elephantiasis forms in Fiji less than 10 per cent. of cases of filariasis. Mikrofilariæ are present in the blood in 36 per cent. (12 out of 33) of cases.

_Chyluria._--Exceedingly rare in Fiji. Theory would demand an obstruction above the point of entry of the lacteals, _viz._, the pre-aortic lymphatic glands, but in cases in temperate regions it may occur without any such lesion. In some of these cases the fluid is not chyle (fat absent), but presumably lymph. A discussion of the mode of production of chyluria, lymph scrotum, elephantiasis, etc., is at present premature; theory has far outrun fact. Too much stress had been laid on the mechanical action of the worms to the almost total exclusion of their (or possibly their larval) toxic action. The above analysis has been made in the hope of acquiring more extended observations similar to those made by Bahr.

_Geographical Distribution._--_Filaria bancrofti_ is known in nearly all tropical countries. It occurs in India, China, Indo-China, Japan, Australia, Queensland, the Islands of Polynesia (with the exception of the Sandwich Islands), Egypt, Algeria, Tunis, Madagascar, Zanzibar, Sudan, etc., the south of the United States of America, Brazil, the Antilles, etc. Whether it is the same species in all cases is questionable.

*Filaria demarquayi*, Manson, 1895.

Syn.: _F. ozzardi_, Manson, 1897.