It bas been already observed that no species of the Acanthoceplialous order of Entozoa has hitherto been found in the Human body, the illustration of this form of the Sterclmintha will therefore be confined to the section treat ing of the general anatomy of the Entozoa.
The Class Calelmintha contains several species of Entozoa which are obnoxious to man ; of these may be first mentioned the Medina or Guinea-worm (Filaria Mcdinensis, Gmel.) This species is developed in the sub cutaneous cellular texture, generally in the lower extremities, especially the fact, sometimes in the scrotum, and also, but very rarely, be neath the Tunica conjunctiva of the eye. It appears to be endemic in the tropical regions of Asia and Africa.
' The length of this worm varies from six inches, to two, eight, or twelve feet; its thick ness from half to two-thirds of a line; it is of a whitish colour in general, hut some times of a dark brown hue. The body is round and sub equal, a little attenuated to wards the anterior extremity. In a recent specimen of small size, we have observed that the mouth was surround ' ed by three slightly raised swellings, which were conti nued a little way along the body and gradually lost ; the body is traversed by two lon gitudinal lines corresponding to the intervals of the two well marked fasciculi of longitu dinal muscular fibres. The caudal extremity of the male is obtuse, and emits a single I spiculum; in the female it is acute and suddenly inflected.
The Filaria 31edincnsis, as has just been observed, is oc casionally located in the close vicinity of the organ of vision ; but another much smaller spe cies of the same Genus of Nematoidea infests the cavity of the eyeball itself.
The Filaria °cull humani was detected by Nordmann in the Liquor Morgagni of the capsule of a crystalline lens of a man who had undergone the operation of extraction for ca taract under the hands of the Baron von Griife. In this in stance the capsule of the lens had been extracted entire, and upon a careful examination half an hour after extraction therewere observed in the fluid above-mentioned two minute and delicate Filaria coiled up in the form of a ring. One of
i. these worms, when examined microscopically, presented a rupture in the mid dle of its body, probably occasioned by the ex tracting needle, from which rupture the intesti nal canal was protruding ; the other was entire and measured three-fourths of a line in length ; it presented a simple mouth without any appa rent papilla•, (as are observed to characterize the large Filaria which infests the eye of the horse,) and through the transparent integument could be seen a straight intestinal canal, sur rounded by convolutions of the oviducts, and terminating at an incurved anal extremity.
The third species of Filaria enumerated among the Entozou liorninis is the Filaria bronchialis (fig. 68); it was detected by Trent Ice in the enlarged bronchial glands of a man : the length of this worm is about an inch ; it is slender, subatten uated anteriorly (a), and emitting the male spiculum from an in curved obtuse anal ex tremity (6).
The next Human Entozoon of the Ne matoid order belongs to the genus Tricho cephalus, which, like is character ized by an orbicular mouth, but differs from it in the capillary form of the anterior part of the body, and in the form of the sheath or preputial covering of the male spieulum. The species in question, the Tricocephalus dispar, Rud. is of small size, and the male (*fig. 69) is rather less than the female. It occurs most eommooly in the ececum and colon, more rarely in the small intestines. Occasionally it is found loose in the abdominal cavity, having perforated the coats of the intestine. The capillary portion of this species makes about two-thirds of its entire length ; it is transversely striated, and contains a simple straight intestinal canal ; the head (a) is acute, with a small simple terminal mouth. The thick part of the body is spirally convoluted on the same plane, and exhibits more plainly the dilated mooiliforrn intestine (6); it terminates in an obtuse anal extremity, from the inner side of which pro ject the intromittent spiculum and its sheath (c, d). The corresponding extremity in the female exhibits a simple foramen, which, like the outlet of a cloaca, serves the office of both anus and vulva.