332 Prof. R. Leuckart on the Developmental 
Notwithstanding all analogies with the other Entozoa, and 
especially with the Tapeworms just mentioned, the Trichine 
diverge in their comportment in this respect: the muscle- 
Trichine, which may be compared to the Cysticerci of muscles, 
regularly originate by self-infection in the bearer of the sexually 
mature intestinal Trichine, whilst the development of the Cysti- 
cerci usually requires infection from without. In other words, 
the embryos from which the muscle-Trichine are produced mi- 
grate in the host of their parents ; while the germs of the Cysér- 
cerct quit their original host and pass imto another species of 
animal. In the complete development of the Tenie, therefore, 
three different bearers usually co-operate, while that of the Zz- 
chine in general only require two. 
But the difference here indicated is by no means of primary 
importance. So little is it such, indeed, that not unfrequently 
the two forms of worms completely change their parts. Just as 
we know that embryos of Trichina introduced from without 
become further developed, under certain circumstances, in the 
muscles even of other animals, so also is it sufficiently well 
known that the bearer of a Tenia solium not unfrequently ac- 
quires Cysticerct by self-infection. That this does not more 
commonly take place, notwithstanding the development of the 
embryos while still in the body of the parent, is explained by 
the presence of a firm egg-capsule, which requires the action of 
the juices of the stomach to set free its vagrant inmate. For 
their further development the germs of Tenia must pass the 
stomach (which, of course, can only occur exceptionally in man), 
whilst the embryos of Trichina, which are produced without egg- 
shells, start upon their migration immediately from the intestine. 
According to my observations, however, there are numerous 
Nematoda in which the emigration of the embryos from the 
original host not only occurs regularly (which is by no means 
the case with the Jrichine), but even constitutes a necessary 
preliminary to further development. 
In the mucous membrane of the stomach of the cat there lives 
a viviparous Strongylide worm hitherto overlooked (Odlulanus 
tricuspis, mihi*), which measures scarcely more than | milli. 
* T append the following diagnosis to characterize this worm, which is 
by no means rare :— 
Ollulanus tricuspis, n. gen. et n. sp.—Small, rather thick worms, with a 
beaker-shaped or poculiform chitinous coating of the mouth-cavity. 
Pharynx slightly muscular, of granular appearance. In the males 
two short and stout, nearly straight spicula, and a bilobed caudal 
hood, each of the lateral wings of which contains six ribs. Female 
with three caudal points. Vulva at some distance before the anus; 
uterus simple. 
