332 ANIMAL PAEASITES. 



thinner, passing in the most various directions, sometimes forward, 

 sometimes backward, up to the level of the vaginal opening, 

 and thence again runs backward, and also passes once more to 

 the other side over the contracted part of the intestine already 

 referred to. At this spot the tube has already become very thin 

 and filiform, but its finer extremity can be traced no further. 

 The convolutions last described form the ovary, and as far as they 

 could be traced, they only present the same phenomena as those 

 of the other nematode worms, of which we shall speak further 

 under the Strongyli. I shall only add a few words upon the 

 eggs themselves. The eggs of both kinds of worms have an 

 external, brownish, tolerably thick shell, distinctly bordered by 

 two outlines, of a longish oval form, or more correctly of the form 

 of a small longish cask, or of a large fish-basket. This shell, 

 however, does not reach to the poles of the oval, but ceases a 

 little from the commencement of these, and from the poles 

 of the egg protrudes a small, light, wart-like body of a roundish 

 shape, which forms, as it were, a sort of cap on the poles. 

 JDujardin says of these eggs : " Les ceufs d'une forme oblongue 

 sont revetus d'une coque resistante, qui se prolonge aux deux 

 extremites en une sorte de goulot court, a travers lequel la mem- 

 brane interne plus diapharie parait faire saillie." Mayer has 

 described this little cap under the name of a " short diverticulum," 

 and this certainly depends upon the formation of the eggs in the 

 fleshy oviduct. They contain sometimes only yelk in course of 

 segmentation, sometimes ready formed, young embryos. The 

 fate of these eggs, with the brood, is undoubtedly to pass 

 outwards, then either to be swallowed probably by various 

 species of animals, which man employs as food, in the bodies of 

 which the brood then migrates onward, and fixing itself in their 

 muscular layers becomes encysted there, or perhaps also to wan- 

 der directly from without into the bodies of their hosts, which, 

 however, appears very improbable to me. That even this question 

 will be cleared up in time by experiment, I am firmly convinced, 

 and I only regret that, from want of material, it has hitherto 

 been impossible for me to administer the mature eggs of 

 Trichocephali. Perhaps my request expressed in letters to 

 the Imperial Medical Society of Vienna, and to two of the 

 most celebrated German pathological and physiological anato- 

 mists, to undertake experiments of this kind, may have a 

 result. In the institution of experiments of this kind, I had 



