Chapter XI: Section II: CESTODA (Tapeworms) (3)

_Tænia abietina_ and other varieties. I can only notice very briefly certain cestodes which either present malformations or which may be regarded as mere _varieties_. First in this series is Weinland’s _T. abietina_. No one who has studied his ‘Beschreibung zweier neuer Tænioiden aus dem Menschen,’ Jena, 1861, can doubt that it is a mere variety of _T. mediocanellata_. The monstrosity described by him as referable to _T. solium_ must also be referred to the beef tapeworm. The variations in the character of cestode proglottides is practically infinite. A museum might be filled with them. Most common with _T. mediocanellata_, these varieties more or less prevail with other species. Thus I have seen them in Tæniæ and Bothriocephali alike. I have obtained segments of _T. mediocanellata_ having sexual outlets on both sides of the proglottis, so regularly disposed in a few segments as to suggest the notion of a new species. The coalescence of several segments into one compound segment is frequent, but the most remarkable specimen that I have seen is one contained in the museum of the Royal College of Surgeons. In the old Hunterian catalogue the specimen is described as “two joints of the _Tænia solium_, with a number of orifices in unequal series on either side.” As stated in the new catalogue of the series, prepared by myself, the “lower segment is furnished with twenty-two sexual orifices, one of which is situated in the central line” on the ventral surface (as in Bothriocephali). References to this and other specimens in the Hunterian Collection will be found below (see _Pittard_). In regard to Weinland’s conjectural _Tænia acanthotrias_, based on the circumstance of his having found a Cysticercus that presented three rows of hooks on its rostellum, I need only say that if such a _Tænia_ were found it would only turn out to be a malformed _T. solium_. The specimens, however, are none the less interesting. Very remarkable and altogether exceptional characters are presented by the strobile of the cestode described by Mr Cullingworth, of Manchester, and of which I possess specimens. Here, apparently, at least two tapeworms are joined together throughout the entire chain of proglottides without intermission. The three margins of each compound segment project at equi-distant angles. Could we have secured the head we should certainly have found six or eight suckers present, since the finest neck-segments showed that the malformation pervaded the entire colony of zooids, sexually mature and otherwise. Mr Cullingworth’s specimen is so remarkable that I subscribe full particulars of the case in his own words. He says:--“A respectable married woman, named Ann H--, forty years of age, residing in Salford, brought to my out-patient room at St Mary’s Hospital, Manchester, on September 3rd, 1873, a few segments of tapeworm as a sample of what she had been passing per anum for about two years. Although never in the habit of taking meat absolutely raw, she told me, on inquiry, that she was particularly fond of tasting it when only partially cooked. The segments were unlike anything I had seen before, and I took them home for examination, ordering the patient meanwhile a draught containing a drachm of the oil of male fern, and giving her strict injunctions to bring to me every fragment that passed away as a result.

“On September 17th she brought me portions of a tapeworm corresponding throughout to the segments I had already seen, and measuring altogether nine feet in length. Unfortunately, the head was not to be found. Along the middle line of every segment in the body a crest or ridge runs longitudinally, and in the centre of the margin of this crest the genital pore is situated. [In 304 segments examined, only four had the genital opening placed laterally. One segment had two openings, viz. one at the lateral margin and the other in the crest.] Underneath the segment there is a longitudinal groove, and the lateral portions are folded together by the apposition of their under surfaces. When hardened in spirit the section of a segment presents a three-branched appearance, the branches being of unequal length, but placed at equal angles. The uterus sends vessels into the crest as well as into the sides of the segment; and the contained ova are exactly like the ova of an ordinary _Tænia mediocanellata_. Wedged in between, or attached to, the segments here and there, is a stunted and ill-shaped joint, with irregular and unequal sides. A mature joint measures from five eighths of an inch to three quarters of an inch in length, and about half an inch in breadth, and the breadth or depth of the crest is usually one eighth of an inch.

“There are only two specimens that I can find on record at all similar to the one here described, and both of these differ from it in several important particulars. Küchenmeister mentions, as a variety of _Tænia mediocanellata_, a tapeworm sent to him from the Cape of Good Hope by Dr Rose. This worm possessed a longitudinal ridge, but he describes its mature segments as ‘extremely massive’--more than an inch in length and 3/5″ in breadth. The genital pores, too, were irregularly alternate, and not situated on the crest. On March 20th, 1866, Dr Cobbold exhibited to the Pathological Society of London a specimen of crested tapeworm which was discovered in the museum of Middlesex Hospital, and to which he proposed to give the name _Tænia lophosoma_ (λόφος, crest; σῶμα, body). The reproductive papillæ were all on one side of the chain of segments, a peculiarity which entirely distinguished it from the Cape of Good Hope variety of Küchenmeister. The head of the creature was wanting. It will thus be seen that my specimen does not correspond with either of these in the situation of the genital aperture. Here it is placed in the crest itself, and not unilaterally, as in Dr Cobbold’s specimen, or alternately, as in Küchenmeister’s. It further differs from the Cape variety in the more moderate dimensions of its proglottides. I have adopted, however, the name suggested by Dr Cobbold in the communication referred to, inasmuch as it sufficiently indicates the principal distinguishing feature of the specimen. I may mention that Dr Cobbold saw the specimen during his visit to Manchester, and that he regarded it as a most remarkable and unique abnormality.”

Further, in connection with abnormal cestodes, I may observe that Weinland’s case of a triple-crowned Cysticercus does not stand alone, since a similar specimen is, I believe, in the possession of the Rev. W. Dallinger. This was removed from the human brain. Curious as this subject is, I cannot dwell upon it. Not only are the mature tapeworms and their Cysticerci liable to present monstrosities, but even also their proscolices or six-hooked embryos. Thus, twelve hooks were observed by Salzmann in the embryo of _T. elliptica_, and Heller also figures two embryos of _T. mediocanellata_ (_T. saginata_, Gœze) with numerous hooklets. Dujardin saw seven in a _Bothriocephalus_ embryo. Occasionally there have been errors of interpretation made by observers. Thus, Diesing has given beautiful figures of _Dibothrium hians_ in such a way as to suggest different degrees of monstrosity affecting the tail end of the strobile; but this splitting has clearly resulted from injury. Thus also, when I removed five specimens of a new cestode (_Diphyllobothrium stemmacephalum_) from the intestines of a porpoise, one of them was cleft nearly half way up the strobile. This had been done by the scissors employed in slitting up the gut; but owing to perfect contraction of the incised edges, it was some time before I discovered that the apparent monstrosity had been artificially produced. Lastly, I may add that many of the older writers were well acquainted with larval and other anomalies. Thus Rudolphi described a two-headed Cysticercus from a Lemur, and also a double-headed _Tænia crassicollis_. This worm had a tripartite body; as had likewise a _Tænia crassicollis_ of which he did not possess the head (_corpore prismatico_). Other monstrosities were described and figured by Bremser and Creplin. Pallas mentions a two-headed Tricuspidaria (_Triænophori nodulosi bicipites_), and, as already stated at p. 97, a double-headed Cysticercus has been obtained from the liver of a sheep.

Before quitting the _Tæniæ_ proper, I may observe that several other species have been indicated, based on ovular and other insufficient characters. To these belong Ransom’s supposed tapeworm, and also Weinland’s _Tænia megaloön_.

BIBLIOGRAPHY (No. 18).--_Bonnet, C._, ‘Œuv. Compl.,’ tom vi, p. 191, 1791.--_Bremser_, Atlas, by Leblond, Pl. iv.--_Chaussat_, ‘Comptes Rendus,’ p. 20, 1850.--_Cobbold_, ‘Catalogue of the specimens of Entozoa in the Museum of the Royal College of Surgeons of England,’ Nos. 118-121, London, 1866.--_Idem_, ‘Worms,’ l. c., p. 78.--_Idem_, “On a Cysticercus from the Human Brain,” ‘Brit. Assoc. Rep.,’ 1870.--_Creplin_, ‘Tænia Monstrum, &c.,’ Berlin, 1839.--_Cullingworth, C. J._, “Notes on a remarkable specimen of Tapeworm (_Tænia lophosoma_, Cobbold),” ‘Med. Times and Gaz.,’ Dec., 1873.--_Davaine_, ‘Les Cestoïdes,’ l. c., p. 570.--_Diesing_, ‘Zwanzig Arten von Cephalocotyleen,’ figs. 1 and 2, taf. ii (aus dem xii, Bd. d. denkschr. d. Math.-nat. Cl. d. k. Akad.), Wien, 1856.--_Dujardin_, l. c., p. 619.--_Heller_, l. c., s. 600.--_Küchenmeister_, l. c., Eng. edit., p. 139.--_Leuckart_, l. c., s. 303 and 465.--_Levacher_, ‘Journ. l’Institut,’ p. 329, 1841.--_Pittard, S. R._, Remarks in his article “Symmetry,” Todd’s ‘Cyclop.,’ vol. iv, p. 848, 1849-52, in which he refers to a monstrous Bothriocephalus (_T. lata_) in the Hunterian Museum, old ‘Catalogue of Nat. Hist.,’ pl. iv, p. 50, No. 205; see also my ‘Catalogue,’ l. c., _supra_, No. 167.--_Ransom_, in Reynolds’ ‘System of Medicine.’--_Rudolphi_, ‘Synops.,’ p. 545 and 598-9, with fig. showing the heads of _Cystic. Simiæ_ (biceps), widely apart, 1819.--_Weinland_ (_T. megaloön_), in Zoolog. Garten, Frankf., 1861, s. 118.--_Idem_, ‘Essay,’ l. c., p. 11.

_Bothriocephalus latus_, Bremser.--This species, though seldom seen in England, is sometimes brought hither by persons who have been residing for a time in foreign countries. It is indigenous in Ireland, and, though by no means common there, has been called the Irish Tapeworm. As regards its distribution in Europe it is much more prevalent in some districts than in others. On this point Leuckart remarks that “foremost amongst these are the cantons of West Switzerland, with the adjacent French districts. In Geneva, according to Odier, almost a fourth part of all the inhabitants suffer from Bothriocephalus. It is also common in the north-western and northern provinces of Russia, in Sweden, and in Poland. In Holland and Belgium it is likewise found, but, on the whole, not so frequently as in the first-named countries. Our German fatherland also harbours them in some districts, especially in eastern Prussia and Pomerania, and there have appeared cases in other places, as in Rhenish Hesse, Hamburg, and even in Berlin; these being apparently spontaneous instances.”

Unlike the ordinary tapeworms, the segments of the broad tapeworm do not individually separate so as to become independent organisms, a circumstance which is highly favorable to the bearer. Its remarkable breadth, and the extremely numerous and closely-packed proglottides, impart a sufficiently distinctive character; but this parasite may be more fully characterised as the largest human cestode at present known, attaining a length of more than twenty-five feet, and sometimes measuring nearly an inch in breadth; the so-called head 1/25″ in width, bluntly pointed at the tip, much elongated or club-shaped, slightly flattened from behind forwards, and furnished with two laterally disposed slit-like fossæ or grooves, but destitute of any armature: anterior or sexually-immature segments of the body extremely narrow, enlarging in a very gradual manner from above downwards; joints of the lower half of the body gradually decreasing in width, but enlarging in depth; sexually-mature segments usually about 1/8 of an inch in depth, but those near the caudal extremity frequently 1/4″, and quadrate in form; body flattened, but not so uniformly as obtains in the ordinary tapeworms, being rather thicker near the central line; total number of joints estimated at nearly 4000, the first sexually-mature ones being somewhere about the six hundredth from the head; reproductive orifices at the central line, towards the upper part of the segment at the ventral aspect, the vaginal aperture being immediately below the male outlet, and both openings surrounded by papillæform eminences; uterus consisting of a single tube, often seen regularly folded upon itself, forming an opaque, conspicuous, centrally-situated rosette; eggs oval, measuring 1/350″ in length by 1/550″ in breadth, having three shell-coverings, and a lid-like operculum at one end, as occurs in the fluke-worms. Owing to the dark color of the egg shells, the uterine rosette is readily seen by the naked eye as a conspicuous deep brown spot at the centre of each successive segment.

The source and development of this parasite are points of considerable interest. The eggs are of comparatively large size, and after expulsion and immersion in water they give passage to beautifully ciliated embryos, which latter produce larvæ furnished with a boring apparatus. These larvæ resemble the six-hooked embryos of other tapeworms. In what animals the larvæ subsequently develop themselves is not ascertained with certainty, but it is probable that persons become infested by eating imperfectly cooked fresh-water fish. Leuckart has suggested that the intermediary bearers are species of the salmon and trout family. Dr Knoch, of Petersburg, thought that there was no need of the intermediate host. He believed that he had succeeded in rearing young broad tapeworms in the intestines of dogs. It was Leuckart who first explained the source of Knoch’s errors of interpretation. Although Knoch administered eggs of _Bothriocephalus latus_ to dogs, and afterwards found young tapeworms of the species in question in the intestines of the dogs, it did not logically follow that any genetic relation (as between the egg-contents and the adult worms) had been thereby established. The circumstance that ripe ova of the Bothriocephalus always contain six-hooked embryos, must alone imply that an intermediate host is necessary for the formation of Cysticerci or measles. If the broad tapeworm could be reared in a direct manner by the administration of Bothriocephalus eggs, there would be no need for the presence of boring hooklets in the proscolex. These are necessary for invading the flesh of some intermediate host.

Dr Fock, of Utrecht, has sent me particulars of an interesting case, and he suggests that infection comes from the little river bleak (_Leuciscus alburnus_). Writing from Utrecht in December, 1877, Dr Fock, after referring to a former case, goes on to say:--“Permettez moi, cher confrère, que je rappelle à votre souvenir que vous avez eu l’obligeance de communiquer au public une observation, de ma main, sur un cas très rare de ver rubanaire, d’un Bothriocephale, chez une petite fille juive. Malheureusement je n’ai pu en donner de plus amples détails, parce que cette enfant n’a plus, depuis ce temps-là, rendu la plus petite parcelle de ver. Il y a maintenant quinze mois, et voilà que de nouveau un cas pareil se présente. Une femme mariée, frisonne, et, cette fois-ci encore, juive, s’est adressée à moi pour la débarasser de son ver. Elle me disait avoir rendu, il y a quelque temps, des fragments, ou plutôt un fragment de la longueur d’un mêtre, d’un ver solitaire, pour lequel elle avait été traitée, sans succès, par son médecin ordinaire. A cause de cela elle s’adressa à moi, et je lui ai repondu qu’elle devrait revenir la première fois qu’elle rendrait de nouveau, spontanément, un nouveau fragment. Après un mois d’intervalle elle est revenue en me montrant un fragment de la longueur d’un demi-mêtre qu’elle venait de rendre spontanément, après avoir jeûni par précepte réligieuse, et deux jours après cela, traitée par l’écorce de grenadier, elle a rendu un Bothriocephale parfaitement conditionné en entier.

“Ce cas me semble assez intéressant pour être communiqué de nouveau, d’abord parce que jusqu’ici personne n’a pu dire par quel chemin a pu s’introduire un tel helminthe, et ensuite parce que ce chemin doit se présenter bien rarement dans nos contrées (ou en Angleterre) puisque dans le courant d’une trentaine d’années ayant rencontré des centaines de tænias, ce cas-ci est seulement le second dont je suis gratifié. Il me semble digne de réflexion que ce cas-ci se présente cette fois-ci de nouveau chez une juive. Est ce cas-ci fortuit, ou bien y-a-t’il un lien de causalité entre ce ver rare et le genre de nourriture ou de boisson de ces bonnes gens? La dame me recontait que, en Frise, il y a un poisson très recherché qui s’appelle en Hollandais blèck, en Anglais blay ou bleak, et dont ils sont très friands, dans lequel, ils rencontrent très souvent un très grand ver rubanaire. Une autre personne me disait avoir été à table chez un ami, qui ne sachant probablement ce qu’il mangeait, savoura avec beaucoup de délice cette friandise dégoutante.”

After describing the specimen, Dr Fock concludes his remarks with a suggestion as to the possibility of introducing tapeworm into the human body by potable water, into which Cysticerci have accidentally found their way. Dr Fock remarks:--“J’ajoute une réflexion par rapport à la provenance des autres tænias, qui jusqu’ici sont introduits par l’usage de la viande non assez cuite ou rôtie, ou saignante; mais, ne se pourrait-il pas que des débris de la chair d’un animal ladre fussent introduits fortuitement dans l’eau, par example, d’un fossé, et que celle-ci employée comme boisson contint des Cysticerques et par ainsi aussi une cause de Tænia? Ce n’est qu’une conjecture que je propose en terminant cet article.”

Although I cannot at all agree with Dr Fock in regarding water as a source of infection in the manner he indicates, yet the still more recently expressed opinions of MM. Bertolus and Duchamp, based on experimental researches, render it tolerably certain that Leuckart’s original surmise was correct, and that we must look to freshwater fishes for the larvæ of the broad tapeworm. In the section of this work devoted to the parasites of fishes I shall make particular allusion to the experiences of Dr Bertolus; but as confirming the view of Leuckart I may here observe, that Bertolus has almost proved that the so-called _Ligula nodosa_ infesting the common trout is merely a sexually incomplete example of _Bothriocephalus latus_. The bleak (_Leuciscus alburnus_) shares with other freshwater fishes the privilege of harbouring a species of _Ligula (L. digramma)_; but whether this form bears any genetic relation to our human _Bothriocephalus latus_ can only be determined by actual experiment. If, as Duchamp and others have either indicated or implied, _Ligula alburni_ is a synonym of the bleak’s cestode in question, then it is evident that the sexually mature form of the _Ligula_ of the bleak is the well-known _L. simplicissima_ of many water birds and of a few other avian species. Probably the bleak-eaters of Holland consume many kinds of freshwater fishes, including various species of the salmon and trout family.

The symptoms occasioned by _Bothriocephalus latus_ do not differ materially from those produced by other tapeworms. According to Odier, as quoted by Davaine, there is not unfrequently a tumid condition of the abdomen, with sickness, giddiness, and various hysterical phenomena occurring at night. Pain in the region of the heart, palpitations, and faintness are also mentioned.

As already hinted, this cestode is very liable to present abnormalities of structure, the proglottides frequently displaying double sexual orifices, with corresponding duplication of the reproductive organs internally. For details respecting the anatomy of _Bothriocephalus_ I must refer to the works of Küchenmeister and Leuckart; and more particularly to the memoir of Drs F. Sömmer and L. Landois, who have supplemented the previous researches of von Siebold, Leuckart, Böttcher, Stieda and others by beautiful investigations of their own. In the pages of ‘Nature,’ for 1872, I gave a _résumé_ of Sömmer’s memoir, which will be found quoted below.

_Bothriocephalus cordatus_, Leuckart.--This species is identical with a worm long ago described by Pallas and Linneus. At present it is only known to infest the residents of North Greenland, but it is probably distributed throughout the north generally. It attains the length of about one foot, and has a small heart-shaped head, whose apex is directed forwards. The neck is so obscure that it may be said to be altogether wanting, the segmentation of the body being well marked immediately below the head. Though so small a species, Leuckart, who first described it, counted between six and seven hundred joints. As in the broad tapeworm, the reproductive orifices are serially disposed along the centre of the ventral line, but a close inspection shows that the folds of the egg-bearing organ are comparatively more numerous. This worm does not appear to be a frequent resident in the human body, though it is by no means uncommon in the dog. Possibly it may yet be found in the inhabitants of some of our northern and western isles.

_Bothriocephalus cristatus_, Davaine.--This cestode measures between nine and ten feet in length, and is characterised by the presence of two remarkable prominences, together forming a sort of rostellum or crest which is covered by numerous minute papillæ. The full-grown segments are less than half an inch in breadth; the body of the parasite being narrower than that of the broad species. The original description of the parasite by Davaine is based on two specimens, one of which, quite perfect, was obtained from a child five years old, under Dr Féréol’s care at Paris. The other was passed spontaneously by an adult residing at Haute-Saône. I have here copied one of Davaine’s original figures of the head of the worm.

BIBLIOGRAPHY (No. 19).--_Bertolus_, “Mém. sur le development du _Dibothrium latum_” (in Appendix to Duchamp’s work, see Bibliog. No. 59).--_Blanchard_, “Recherches, &c.,” ‘Ann. des Sci. Nat.,’ ser. 3, Zool., Pl. 11, 12, 1848.--_Böttcher_, “Studien ueber den Bau des _Both. latus_,” ‘Virchow’s Archiv,’ s. 97 _et seq_, 1864.--_Bremser_, l. c., Bibl. No. 1, s. 88, 1824.--_Chiaje_, ‘Compendio, &c.,’ Tab. iii, figs. 1-5, 1833.--_Cobbold_, ‘Entoz.,’ p. 289, 1864.--_Idem_, “Remarks on the Broad Tapeworm” (with a letter from Dr Fock), the ‘Veterinarian,’ July, 1878.--_Creplin_, in Ersch and Gruber’s ‘Encyclop.,’ 1839, p. 296.--_Davaine_, ‘Traité,’ l. c., 1860; 2nd edit. (_passim_), 1877.--_Idem_, art. ‘Les Cestoïdes,’ l. c., Bibl. No. 2, p. 580-591, 1876.--_Dujardin_, l. c., Bibl. No. 1, p. 612, 1845.--_Eschricht, D. F._, ‘Anat-physiol. Untersuchungen ueber die Bothriocephalen,’ Breslau, 1840.--_Fock_ (see Cobbold).--_Heller_, ‘Darmschmarotzer,’ l. c., s. 606, 1876.--_Knoch_, ‘Petersburger Med. Zeitschrift,’ 1861.--_Idem_, ‘Die Naturgeschichte des breiten Bandwurms (_B. latus_, auct.),’ St Petersburg, 1862.--_Küchenmeister_, ‘Ueber cestoden,’ l. c., 1853.--_Leuckart_, ‘Die Blasen Bandwürmer,’ 1856.--_Idem_, ‘Die mensch. Par.,’ Bd. i, s. 414-448, und 757, 1863; and Bd. ii, s. 866, 1876.--_Owen_, Todd’s ‘Cyclop.,’ 1837.--_Sömmer_ und _Landois_, aus Sieb. und Köll. Zeitschr., ‘Beiträge zur Anatomie der Plattwürmer,’ Leipsig, 1872; see also the _résumé_ in ‘Nature’ for Aug., 1872, p. 278.--_Wawruch_, ‘Pract. Monograph. d. Bandwürm-Krankheit,’ 1844, s. 33.

_Echinococcus hominis_ (the common hydatid).--This larval entozoon has acquired various names according to the kind of bearer in which it happens to have been found; but all the true hydatids or acephalocysts, whether infesting man or animals, are referable to one and the same species of parasite. They have been termed _Echinococcus hominis_, _E. veterinorum_, _E. polymorphus_, _E. exogena_, _E. endogena_, _E. multilocularis_, according to circumstances. All of them represent a juvenile stage of the _Tænia echinococcus_ or hydatid-forming tapeworm which infests the dog and wolf. Experimental proof of this fact has been furnished by Von Siebold (1852), Haubner, Leuckart, Küchenmeister, Van Beneden, Naunyn, Nettleship, Krabbe, and others.

The first successful rearing of _Tæniæ_ with human hydatids was accomplished by Naunyn (1864), his results being subsequently verified by Krabbe and Finsen (1865). Zenker, Ercolani, and several others, including myself, also conducted feeding experiments with human hydatids which were attended with negative results. In the case of one of my experimental dogs the animal was liberated by an ill-disposed person before I had opportunity to destroy it. As the experiment was carefully conducted, the animal may have proved a source of fresh echinococcus-infection. Mr E. Nettleship’s eminently successful experiment was made with hydatids obtained from a sheep. The converse experiment, namely, that of rearing hydatids with the mature proglottides of _Tænia echinococcus_ administered to animals, has been performed most successfully by Leuckart, and by Krabbe and Finsen; by the former in the pig, by the latter in a lamb, with tapeworms that had also been reared by experiment. Zenker, later on, reared the _Tænia_ from hydatids obtained from an ox.

The sexually mature _Tænia echinococcus_ may, for the purposes of diagnosis, be characterised as a remarkably small cestode, seldom reaching the fourth of an inch in length and developing only four segments, including that of the head; cephalic extremity capped by a pointed rostellum, armed with a double crown of comparatively large-rooted hooks, from thirty to forty in number; the four suckers prominent, and succeeded by an elongation of the segment forming the so-called neck; final segment, when sexually mature, equalling in length the three anterior ones; reproductive papilla at the margin of the proglottis rather below the central line; proscolex or embryo giving rise to the formation of large proliferous vesicles, within which the scolices or echinococcus-heads are developed by gemmation.

When an animal is fed with the mature proglottides of _Tænia echinococcus_ the earliest changes that take place are the same as obtain in other cestodes. The segments are digested; the shells of the ova are dissolved; the six-hooked embryos escape. The embryos bore their way into the organs of circulation, and thence they transfer themselves to the different organs of the host; being especially liable to take up their abode in the lungs and liver. Having arrived at this, their resting stage, the embryos are next metamorphosed into hydatids. According to Leuckart’s investigations the juvenile hydatid is spherical at the earliest stages; being surrounded by a capsule of connective tissue formed from the organs of the host. After removal from its capsular covering, the vesicle consists of a thick laminated membrane, forming the so-called cuticular layer, and a central granular mass, which subsequently becomes enveloped by a delicate granular membrane. At the fourth week the echinococcus capsule measures about 1/25″ in diameter, its contained hydatid being little more than half this size. Its future growth is by no means rapid, seeing that at the eighth week the hydatid has attained only the 1/15″ in diameter. At this period the central granular mass develops a number of nucleated cells on the inner surface of the so-called cuticle. These cells, which at first are rounded or oval, become angular or elongated in various directions, and even distinctly stellate; and in this way a new membrane is formed, constituting the so-called inner membrane or granular layer. The intermediate stages between this condition and that of the fully-formed echinococcus hydatid have not been satisfactorily traced in detail; nevertheless, Krabbe and Finsen’s experiment on a lamb showed that within a period of little more than three months well-developed echinococcus-heads may be formed in the interior of the vesicles. It is thus clear that the production of scolices immediately follows the formation of the granular layer, and this is succeeded, though not invariably, by the formation of daughter- and grand-daughter-vesicles, which are sometimes termed “nurses.” These latter may be developed exogenously or endogenously.

The appearance of hydatids varies very much according to their mode of formation, to the kind of host in which they are present, and to the character of the organs in which they happen to take up their residence. The so-called exogenous type occurs sparingly in man, whilst the endogenous type is very abundant. The peculiar form known as the multilocular echinococcus is probably a mere variety of the exogenous type. The exogenous and endogenous hydatids may coexist in the same bearer. In the lower animals we commonly find the organs of the body occupied by numerous lobulated cysts, varying in size from a walnut to a goose’s egg, but sometimes rather larger. They are rarely solitary, being particularly liable to occupy both the liver and lungs in the same animal. The viscera are sometimes crowded with cysts. The hydatids do not usually protrude much beyond the surface of the infested organ, but lie imbedded within its parenchymatous substance.

The multilocular variety was first described by Virchow. In reference to it Leuckart writes as follows:

“Hitherto we know this growth only from the liver, in which it forms a firm, solid, and tolerably rounded mass of the size of the fist or even of a child’s head. At first sight it looks more like a pseudoplasm than a living animal parasite. If you cut through the tumour, you recognise in its interior numerous small caverns, mostly of irregular shape, and separated from one another by bundles of connective tissue, more or less thick, and including a tolerably transparent jelly-like substance. In the intervening stroma a blood-vessel or a collapsed bile-duct runs here and there; but there is nowhere any trace of true liver substance. The outer boundaries of the tumour are in most cases pretty well defined, so that the attempt to cut these growths out is not difficult. In particular spots, especially at the surface, one sometimes sees white, moniliform, jointed lines passing off from the tumour, and even thicker terminations which, perhaps, expand in the neighbouring liver-parenchyme into new (multilocular) groups of different size. In one case, recorded by Virchow, the growth extended, together with Glisson’s capsule, a long way towards the intestine.” To this description it may be added, that the growth on section presents an appearance not altogether unlike alveolar colloid, having, in point of fact, been confounded with that pathological product, with which, however, as stated by Virchow, it has nothing in common. This is proved not only by the occurrence of the pathological features above mentioned, but also, more particularly, by the well-ascertained presence of echinococcus-heads in most of the so-called alveoli. Several hypotheses have been broached with the view of explaining the mode in which these multilocular hydatid growths are formed. Virchow thought that the echinococcus vesicles were primarily formed in the lymphatic vessels, whilst Schröder van der Kolk supposed that they originally took up their abode in the biliary ducts. Although, thanks to the courtesy of Professor Arnold Heller in giving me a specimen, I have been enabled to confirm much that has been written in respect of the morbid appearances, I can add nothing towards the solution of the difficulty in question. Until lately it was supposed that the multilocular variety of hydatids only existed in man, but Professor Böllinger has encountered it in the liver of a calf.

Selecting any ordinary fresh example of the exogenous kind, and laying the tumour open with a scalpel, we notice in the first instance an escape of a clear transparent, amber-coloured fluid. This previously caused the distension of the sac. If the tumour is large, this escape will probably be followed by a falling in, as it were, of the gelatiniform hydatid membrane, in which case the inner wall of the external adventitious investment or true fibrous cyst will be laid bare. If the hydatid be next withdrawn from the cyst, it will be seen to display a peculiar tremulous motion, at the same time coiling upon itself wherever there is a free-cut margin. Further examination of portions of the hydatid will show that we have two distinct membranes; an outer, thick, laminated, homogeneous elastic layer (the _ectocyst_ of Huxley), and an internal, thin, soft, granulated, comparatively inelastic layer--the _endocyst_ of the same author. The terms are convenient. The ectocyst is structureless, consisting of a substance closely allied to chitine. For this and other reasons it has been called the cuticular layer, but the endocyst is the essential vital part of the animal, representing a huge compound caudal vesicle. In an hydatid from the zebra, Huxley found that the endocyst was “not more than 1/2000th of an inch in thickness, being composed of very delicate cells of 1/2000″ to 1/5000″ in diameter, without obvious nuclei; but often containing clear, strongly refracting corpuscles, generally a single one only in a cell.” Prof. Huxley adds: “These corpuscles appear to be solid, but by the action of dilute acetic acid the interior generally clears up very rapidly, and a hollow vesicle is left of the same size as the original corpuscle. No gas is developed during this process, and sometimes the corpuscles are not acted upon at all by the acid, appearing then to be of a fatty nature. A strong solution of caustic ammonia produces a concentrically laminated or fissured appearance in them. Under pressure and with commencing putrefaction a number of them sometimes flow together into an irregular or rounded mass.”

The precise mode of development of the echinococcus-heads or scolices has been a subject of lengthened discussion between Leuckart and Naunyn. According to Leuckart the earliest indication of the scolex consists of a slight papillary eminence on the inner surface of the granular endocyst. After a short period this prominence displays in its interior a vacuole-like cavity, the latter being occupied, however, with a clear limpid fluid. Its margins become more and more clearly defined, until the cavity is by and by seen to be lined with a distinct cuticular membrane. The papilla increasing in size, becomes at first elongated or oval, eventually scoleciform, or even, perhaps, a true echinococcus-head. Thus far the description bears out, in a measure, the theoretical notions entertained by the older authors; but the developmental process does not stop here. The scolex-development has now to sacrifice itself by developing in its interior a brood of scolices or echinococcus-heads. In other words, it becomes transformed into the so-called brood-capsules of Leuckart and other authors. These structures were previously well known to Professors Erasmus Wilson and George Busk. Mr Wilson spoke of the capsule as “_a delicately thin proper membrane_, by which the Echinococci are connected with the internal membrane of the acephalocyst” (‘Med.-Chir. Trans.,’ 1845, vol. xxviii, p. 21). Mr Busk described the echinococcus-heads as “attached to a common central mass by short pedicles, which appear to be composed of a substance more coarsely granular, by far, than that of which the laminæ of the cyst are formed. This granular matter is prolonged beyond the mass of Echinococci into a short pedicle common to the whole, and by which the granulation is attached to the interior of the hydatid cyst.” What Mr Busk here describes as a granulation can only be equivalent to the brood-capsule and its entire contents, but he elsewhere speaks of the capsule itself as a “delicate membranous envelope.” It should be borne in mind that Busk’s paper was communicated to the Microscopical Society so early as the 13th Nov., 1844; being published in the ‘Transactions’ for that year.

In the completely developed state the echinococcus-heads exhibit somewhat variable characters as to size and form, the latter differences being, for the most part, dependent upon their degree of contraction and vitality. In the perfect condition they vary from the 1/60″ to the 1/100″ in diameter, being usually about the 1/80″. They are solid, and when stretched out exhibit an hour-glass-like constriction at the centre of the body, which divides the scolex into an anterior part supporting the rostellum and suckers, and a posterior part which has been compared to the caudal vesicle of ordinary Cysticerci. The rostellum supports a double crown of hooks, but the disparity of the two series is scarcely sufficiently marked to render their distinction obvious. The hooks of the smaller row vary in size from 1/1040″ to 1/830″ of an inch, whilst those of the larger series are from 1/830 to 1/555″. In all instances the root-processes are incompletely developed, and consequently vary in thickness. They are, as Leuckart also has stated, apt to exhibit abnormalities.

In regard to the development of the echinococcus-heads it further remains for me to observe that a distinct water-vascular system is recognisable in the scolices. By the intervention of the pedicle of the scolex this system is connected with the brood-capsule, and also with the vessels of the maternal endocyst. In the scolex there exists a circular channel immediately below the rostellum, and this ring, on either side, gives off two vessels which pass downwards in a tortuous manner, internally, until they arrive at the pedicle where they unite to form two channels, which latter are continued into the vascular system of the maternal endocyst. In the retracted condition their position, of course, becomes very much altered, and they form loops on either side of the central line which marks the space leading down to the inverted head. Neither Prof. Huxley nor myself have seen these vessels, which Leuckart observed in the scolex itself, but Huxley discerned some apparently loose cilia in the granular parenchyma of the body; their longitudinal measurement being about the 1/3500 of an inch.

As regards the production of “nurses” by the phenomenon of proliferation, I can only remark that the endocyst is primarily concerned. The secondary and tertiary vesicles must be regarded as so many special bud-developments which, instead of becoming brood-capsules, become daughter-vesicles and grand-daughter vesicles, constantly developing in their interior secondary and tertiary brood-capsules and scolices, but sometimes, it would appear, developing neither the one nor the other. This is the view of Naunyn, which is somewhat opposed by Leuckart, who holds that the vesicles ordinarily arise from within the layers of the ectocyst. Speaking of these daughter-hydatids Leuckart remarks that “Naunyn denies that they take their origin between the lamellæ of the mother bladder--a fact, however, which, in agreement with Kuhl and Davaine, I have seen more than once and have followed out step by step.” For my own part I incline to the belief that the process as observed by Leuckart is exceptional, and that under ordinary circumstances it occurs as Naunyn has described it. Thus the long and short of the whole matter appears to be that the endocyst is capable of forming solitary scolices. Some of the scolices become differentiated to form brood-capsules, a portion of whose individual echinococcus-heads may, in their turn, become secondary brood-capsules, whilst others fail to become either scolices or brood-capsules. It accords with our knowledge of the general plan of development to believe that the daughter and grand-daughter hydatids are likewise peculiarly modified scolices. They are, in short, buds of the endocyst.

The distribution of hydatids throughout the organs of the bearer, and their prevalence in particular countries, has especially engaged my attention. I have personally examined upwards of a thousand preparations of entozoa in our public collections; and of these, 788 are preserved in the anatomical and pathological museums of the metropolis. By this inspection I have obtained a tolerably accurate knowledge of the pathology, localisation and effects produced by the presence of bladder-worms in at least 200 unpublished cases of hydatid disease. Most of our museums exhibit one or more specimens that are unique. After making certain necessary deductions, I find that I have 192 new cases to add to the 135 cases of hydatid disease that I had previously recorded, affording a total of 327 cases available for statistical purposes. If an analysis of these cases be made and compared with the statistics furnished by Davaine, and if the whole be reduced to the lowest number of practically available terms, we at length obtain a result which, although it may be only approximatively correct, is nevertheless of much practical value and significance. The statistics in question stand as follows:

+-----------------------------+----------+-----------+--------+
| Organs affected. | Davaine. | Cobbold. | Total. |
+-----------------------------+----------+-----------+--------+
| Liver | 165 | 161 | 326 |
| Abdomen, including spleen | 26 | 45 | 71 |
| Lungs | 40 | 22 | 62 |
| Kidney and bladder | 30 | 23 | 53 |
| Brain | 20 | 22 | 42 |
| Bones | 17 | 16 | 33 |
| Heart and pulmonary vessels | 12 | 13 | 25 |
| Miscellaneous | 63 | 25 | 88 |
+-----------------------------+----------+-----------+--------+
| Total | 373 | 327 | 700 |
+-----------------------------+----------+-----------+--------+

In the main Davaine’s table and my own show a remarkable correspondency, as is seen in the numbers referring to hydatids of the liver, heart, and bones respectively. Where our results do not correspond the explanation of the discrepancy is sufficiently simple. The abdominal cases here credited as such in Davaine’s table are placed by him under _pelvis_, whilst the abdominal cases in my own table not only include the pelvic hydatids, but also two _spleen_ cases, and nineteen others from the peritoneum and intestines.

As the facts here stand, the liver cases comprise nearly 46-1/2 per cent. In a large number of cases the entozoon has taken up its abode in organs of vital importance. If statisticians and officers of health would obtain an adequate conception of the fatal capabilities of parasites, they should consider these data. In 6 per cent. of all these cases the bladder worm has found its way into the brain, and of course proved fatal to the bearers; in about 3-1/2 per cent. more they took up their residence in the heart, also proving fatal; whilst of all the other cases put together I reckon that not less than 15 per cent. were concerned in bringing about the death of their hosts. I probably underrate the fatal capabilities of echinococcus disease when I express the conviction that hydatids prove fatal to 25 per cent. of all their human victims.

The recently published analysis of 983 cases by Dr Albert Neisser affords similar results. Of these, 451 were referable to the liver, or 45·765 per cent. The other cases, reduced as above, show in the main a similar correspondency.

It may be asked if these facts afford us any assistance in determining the amount of injury that we, as a people, sustain either directly or indirectly from hydatids. On carefully reviewing all the data before me, I may say that it is difficult to draw very precise conclusions; albeit it is not mere guess-work when I assert that in the United Kingdom several hundred human deaths occur annually from this cause. In some other countries the proportion is far greater; the oft-quoted case of Iceland, where the disorder is fatally endemic, still standing at the head of the afflicted territories.

Our Australian colonies are probably entitled to the next place of distinction in this respect. We have strong and recent evidence of the truth of this statement. Thus a writer in the ‘Australian Med. and Surg. Review’ says: “This disease is becoming unpleasantly frequent, and at present we have no reliable mode of treatment, either theoretical or empirical.” Another writer observes (‘Melbourne Argus,’ May 18th, 1874), “Hydatid disease is endemic in this colony; and, though not so constantly met with as in Iceland, we may probably claim the doubtful honor of holding the second place in the list of countries so affected.” In the ‘Argus’ for June 20th of the same year, another writer refers to the frequent notices of cases of hydatids published in the various local newspapers. A retired medical man, the late Mr J. P. Rowe, writing in the ‘Melbourne Leader’ (Sept. 7th, 1872), incidentally remarked on the “notable increase of hydatid disease in the human subject.” Again, still more satisfactory evidence is afforded by a reviewer in the ‘Leader’ of the 31st January, 1874. Commenting on my manual, he not only takes occasion to speak of the prevalence of hydatids generally, but also supplies that kind of accurate statistical evidence of which we so much stand in need. He gives the following table, showing the number of _deaths_ from hydatids in Victoria for eleven years. It is instructive in many ways.

+------------------------------+--------+----------+--------+
| Years. | Males. | Females. | Total. |
+------------------------------+-------------------+--------+
| 1862 | 3 | 2 | 5 |
| 1863 | 3 | 2 | 5 |
| 1864 | 6 | 3 | 9 |
| 1865 | 9 | 6 | 15 |
| 1866 | 18 | 7 | 25 |
| 1867 | 13 | 12 | 25 |
| 1868 | 21 | 12 | 33 |
| 1869 | 12 | 10 | 22 |
| 1870 | 10 | 7 | 17 |
| 1871 | 6 | 9 | 15 |
| 1872 | 24 | 5 | 29 |
+------------------------------+-------------------+--------+
| Total deaths in eleven years | 125 | 75 | 200 |
+------------------------------+--------+----------+--------+

To employ the writer’s own words, “this mortality gives only a faint notion of the extreme prevalence of hydatids in Victoria, since numbers of cases are cured by tapping, and otherwise by medical treatment, or by spontaneous bursting of the cysts.” Hydatids are often found post mortem where their presence has never been suspected during life. “To meet with hydatids as a cause of deranged health is now a matter of daily expectation with every medical practitioner.” Lastly, Dr Dougan Bird, in his able brochure on ‘Hydatids of the Lung,’ fully confirms these statements, remarking that the rich and poor of the Australian metropolis suffer just as much from hydatids as do either the shepherds of the western plains, or the miners of Ballarat and Sandhurst.

Such are the facts from Australia. As regards home evidence, so far as I am aware, little or nothing has been done towards securing an accurate estimate of the mortality in England from echinococcus disease. The reports of the Registrar General give no sufficient sign. The explanation is not far to seek, since for the most part hydatids are either classed with diseases of the liver, or with those of the other organs in which they happen to have been present.

One of the most valuable contributions to our knowledge of the prevalence of hydatid disease affecting animals is that supplied by Dr Cleghorn, from a statistical table constructed by the executive commissariat officers stationed at Mooltan. The record in question shows that out of 2109 slaughtered animals, no fewer than 899 were affected with hydatid disease. This is equal to more than forty-two per cent. In the majority of cases, both the lungs and liver were affected, cysts were found 829 times in the liver and 726 times in the lungs. In a few instances they were present in the kidneys, and also occasionally in the spleen. The inference from all this is that in India, if not elsewhere, the echinococcus disease is much less common in man than it is in animals. The explanation is simple enough, since cattle have more ready access to, and less scruple in partaking of filthy water and food in or upon which the eggs of the _Tænia echinococcus_ abound.

Into purely professional questions connected with the treatment of the echinococcus malady I do not here enter; nevertheless, in connection with hygiene I may observe that the prevalence of hydatids in any country is strictly dependent upon the habits of the people. The close intimacy subsisting between the peasantry and their canine companions is the primary source of the endemic; and where dogs are not kept, it is well nigh impossible that the disease should be contracted. The fact that every Icelandic peasant possesses, on an average, six dogs, and that these dogs share the same dwelling (eating off the same plates and enjoying many other privileges of intimate relationship) sufficiently explains the frequency of hydatids in that country. According to Krabbe, the sexually mature _Tæniæ_ occur in 28 p. c. of Icelandic dogs, whereas in Copenhagen he found it twice only in 500 dogs examined. In his work (quoted below, p. 58, or Fr. Edit., p. 60) Krabbe comments on a sensational passage which, in my introductory treatise (p. 283), I had quoted from a popular memoir by Leuckart (‘Unsere Zeit,’ s. 654, 1862). The practitioners whom we had spoken of as “quacks” are mostly homœopaths; and it appears that even those who are not in any legal sense professional men “treat their patients much in the same way as ordinary medical men.” It simply comes to this, that, instead of _dog’s excrement_ forming with the aforesaid “quacks” a conspicuous or common remedy (as Leuckart’s description had led me to infer), this nasty drug is now rarely administered, and by the grossly ignorant only.

Up to the present time no person has seen the _Tænia echinococcus_ in any English dog which has not been previously made the subject of experiment, but considering the prevalence of hydatid disease amongst us, there can be no doubt that English dogs are quite as much if not more infested than continental ones. Probably, at least one per cent. of our dogs harbour the mature tapeworm. Certainly a great deal of good might accrue from the acquisition of more extended evidence respecting the prevalence of this and other forms of entozoa infesting man and animals in this country.

From Schleissner’s table it appears that hydatids are more frequent in women than in men. Apparently, it is not so in Australia. As regards Iceland the explanation must be sought for in the different habits of life. No doubt, water used as drink by women is constantly obtained from supplies in the immediate neighbourhood of dwellings, and in localities to which dogs have continual access. The comparative rarity of the echinococcus disease amongst sailors is not so much dependent upon the circumstance that seamen’s diet usually consists of salted provisions, as upon the fact that these men can seldom have opportunities of procuring water from localities where dogs abound. In regard to water drinking, there is ground for believing that the addition of a very little alcohol is sufficient to destroy the six-hooked embryos of _Tænia echinococcus_ whilst still _in ovo_; and there is no doubt that water raised to a temperature of 212° Fahr. will always ensure the destruction of the larvæ. Boiled water by itself is by no means palatable. The reason why the upper classes comparatively seldom suffer from hydatids may be attributed to the circumstance that those few who drink water take the very proper precaution to see that it is either “pump” or fresh spring water in which no living six-hooked embryos are likely to exist. So far as hydatids are concerned, wine and beer drinking is preferable to water-drinking; yet if water is carefully filtered no evil of the parasitic kind can possibly result from its imbibition. An ordinary charcoal filter will effectually prevent the passage of the ova, since their diameter is nearly 1/370 of an inch.

From what has been stated it follows that personal and general cleanliness are eminently serviceable as preventions against infection, but to ensure perfect success other precautions must be exercised, especially in relation to our contact with and management of dogs. Leuckart puts this very clearly when he says:--“In order to escape the dangers of infection, the dog must be watched, not only within the house, but whilst he is outside of it. He must not be allowed to visit either slaughter-houses or knackeries, and care must be taken that neither the offals nor hydatids found in such places are accessible to him. In this matter the sanitary inspector has many important duties to perform. The carelessness with which these offals have hitherto been disposed of, or even purposely given to the dog, must no longer be permitted if the welfare of the digestive organs of mankind is to be considered. What blessed results may follow from these precautions may be readily gathered from the consideration of the fact that, at the present time, almost the sixth part of all the inhabitants annually dying in Iceland fall victims to the echinococcus epidemic” (l. c., s. 654). Similar measures had previously been recommended in less explicit terms by Küchenmeister, who in effect remarked that the principal thing was to ensure the destruction of the echinococcus vesicles. He also recommended the expulsion and annihilation of the _Tænia echinococcus_. In order to carry out this idea, it was suggested by Dr Leared that every dog should be periodically physicked, and that all the excreta, tapeworms included, should be buried at a considerable depth in the soil. I advised, however, that in place of burying the excreta, _they should, in all cases, be burnt._ I had, indeed, long previously urged this measure (in a paper “on the _Sclerostoma_ causing the gape-disease of fowls,” published in 1861), with the view of lessening the prevalence of entozoa in general, whether of man or animals. The rule I suggested stood as follows:--_All entozoa which are not preserved for scientific investigation or experiment should be thoroughly destroyed by fire, when practicable, and under no circumstances whatever should they be thrown aside as harmless refuse._ As an additional security I recommended that boiling hot water be occasionally thrown over the floor of all kennels where dogs are kept. In this way not only would the escaped tapeworms be effectually destroyed, but also their eggs and egg-contents, including the six-hooked embryos. These measures were again advocated at the Cambridge Meeting of the British Association in 1862, and also more fully in a paper communicated to the Zoological Society, during the autumn of the same year (‘Proceedings,’ vol. xxx, pt. 3, pp. 288, 315).