The mature strongyloides (Fig. 186) is a minute, slender worm, measuring 2-3 mm. in length by 0·06 mm. in breadth. No male parasite has been discovered. The adult female i eadily recognized by her dimensions, and by the string of five or six ellipsoidal eggs (0·01 mm. by 0·034 mm.) visible about the centre of the body.
As Kanazy has shown, the parasite 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 develop in the intestinal wall, so that
Fig. 185.—Strongyloides stercoralis. (Partly after Looss.)
a. Young larva from fæces; b, mature larva; c, head.
before leaving the host, unless during violent purgation, the larva has escaped and is swimming about in the fæces, as already described, with great vigour, especially when these are fluid. Only in the event of violent purging do the ova appear in the stools. Such ova (Fig. 168, d) are readily recognized by the way in which they are strung together, end to end, inside a delicate tube. On leaving the host, unless they have access to some non-putrefying fluid, the larvæ soon die; it is necessary, therefore, if we would follow their further development, to mix the fæces with water. If this mixture be kept at a low temperature the young rhabditiform larva develops into a filariform larva which, on reaching its host, assumes the mature parasitic form already alluded to. If, on the
