Chapter XVIII: Section IV: PART I.--ACANTHOCEPHALA (Thornheaded worms)

_Echinorhynchus gigas_, Goeze.--There is but one recorded instance of the occurrence of this entozoon in the human body. This is the oft-quoted case by Lambl, given in the ‘Prager Vierteljahrschrift’ for 1859. Lambl, indeed, described it as a separate species (_E. hominis_), but as the worm was a sexually-immature female, its identification with _E. gigas_, notwithstanding Schneider’s great authority, can hardly be regarded as absolutely certain. The worm was found in the small intestine of a boy of nine years, and measured only rather more than the fifth of an inch in length. As Leuckart hints, the worm may be _Echinorhynchus angustatus_, or possibly the _E. spirula_, a species found in various South American apes (_Cebus_ and _Jacchus_), and also in the Barbary ape (_Inuus_).

In 1872, Welch, unaware of Lambl’s case, announced the discovery of “the presence of an encysted Echinorhynchus in man.” The minute parasite found by him occurred in a soldier, thirty-four years of age, who died at Netley, but who had contracted the worm in India. “It was situated in the jejunum, immediately beneath the mucous coat, and formed an oval prominence in the interior of the gut.” Speaking with great confidence, this able microscopist further remarks:--“The character and arrangement of the hooklets unequivocally shadowed forth a species of Echinorhynchus for the first time discovered as a representative of the Acanthocephala in the human body.” Along with his elaborate description Welch gives several figures; but these, so far from producing conviction as to the accuracy of his inferences, have unfortunately led me to believe that the parasite in question would be more properly referred to the _Pentastomidæ_. But for Heller’s acquiescence I might have more fittingly noticed this worm elsewhere. Davaine falls into the same view, and moreover accepts Lewis’s “Echinorhynque du Chien,” which I have shown to be a nematode (_Cheiracanthus robustus_). It is thus that serious errors creep into the literature of parasitism.

In the adult state the female _Echinorhynchus gigas_ is a huge species, occasionally reaching two feet in length, with a breadth of one third of an inch. The male rarely exceeds three inches. This worm is common in swine, both wild and domesticated. According to Schneider the embryos take up their residence in the grubs or larvæ of the cockchafer (_Melolontha vulgaris_), a discovery which very readily explains the manner in which hogs become infested. Whether _E. gigas_ be a human parasite or not, it is certainly very injurious, not to say destructive, to swine. Although this parasite must be quite common in England I have experienced great difficulty in procuring specimens. In the second book of this work I shall give some interesting particulars furnished by the memoir of Prof. Verrill and privately by Mr George Wilkins. (See ‘Parasites of the Pachydermata’.)

BIBLIOGRAPHY (No. 35).--_Blanchard_, in ‘Cuvier’s Règne Animal,’ tab. 35 (good fig.), and in ‘Ann. d. Sci. Nat.,’ ser. xii.--_Bremser_, ‘Icones,’ tab. vi.--_Cobbold_, “Parasites of the Hog,” the ‘Veterinarian,’ 1875.--_Idem_, ‘Manual,’ l. c., p. 123.--_Davaine_, l. c., ‘Syn.,’ p. 83.--_Diesing_, l. c., ii, p. 2.--_Dujardin_, l. c., p. 503.--_Goeze_, l. c., s. 143 (good figs.).--_Gurlt_, l. c., s. 367.--_Heller_, ‘Darmschmarotzer,’ l. c., s. 663.--_Lambl_, l. c., _supra_, Feb., 1859.--_Leuckart_, l. c., Bd. ii, s. 729; also in ‘Bibl. Univ.’ for March, 1863, and in ‘Ann. Nat. Hist.,’ vol. xii, 1863.--_Owen_, l. c., in ‘Todd’s Cyclop.’ (figs. after Cloquet).--_Rudolphi_, ‘Synops.,’ pp. 63 and 310.--_Schneider_, in ‘Arch. f. Anat. und Phys.,’ 1868.--_Idem_, in ‘Sitzungsb. der Oberhess. Gesellsch. f. Nat.,’ &c., 1874 (quoted by Leuckart); see also ‘Ann. Nat. Hist.,’ 4th series, vol. vii, p. 441, 1871.--_Verrill_, ‘The external and internal Parasites,’ &c., l. c., p. 109.--_Welch_, “The presence of an Encysted Echinorhynchus in Man,” ‘Lancet,’ Nov. 16, p. 703, 1872.--_Westrumb_, ‘De Helm. Acanth.’ (good figs.), 1821.