448 Second Report of Experiments of the 
nocephaluin has been described by Von Linstow. Out of a total 
of thirty species, nineteen are covered externally with cilia, and 
eleven are without cilia. The ciliated covering present in many 
forms, including Fasciola hepatica, seems to indicate that the 
embryo is destined to be libeiated in water, and to search for 
its molluscan bearer by swimming. But where the embryo is 
devoid of any ciliated covering, its chances of meeting with a 
host will be greatly increased by this habit on the part of 
various snails and slugs. Even with ciliated embryos infection 
may occur in both ways. In the case of land-molluscs — and 
the number of larval trematodes known to inhabit these has 
been largely increased by recently published observations of 
Professor Ercolani * — this mode of infection from the swallowed 
eggs would seem to be far more probable than the entrance of 
a free embryo either through the skin or into the pulmonary 
chamber. 
Professor Leuckart has quite recently published a paper,! in 
which he states that he has discovered one reason of the want 
of success which had hitherto attended infection experiments. 
He has found that Limnceus pereger is at least one of the inter- 
mediate hosts of the liver-fluke, but that it is only the very 
youngest and smallest individuals that are liable to infection. 
The discovery was made in the following way. He had 
obtained, as he believed, some specimens of Limnceus trunca- 
tulus, and having exposed them to infection, succeeded in 
obtaining a further development of the embryos. But a closer 
examination of his snails showed that he was really dealing 
not with Limnceus truncatulus but, owing to a most fortunate 
mistake, with young specimens of L. pereger. According to 
his account, the ciliated embryo wanders into the young snail, 
and losing its layer of ciliated cells, changes into a sporocyst, 
within which redia» (or germinal sacs provided with pharynx 
and intestine) develop. These redia? are set free from the 
sporocyst, and within them are developed spherical masses of 
cells. But here, unfortunately, his observations end, for he has 
not been able to trace the further growth of these germinal 
spheres, though we may conjecture that they develop into 
the brood of cercariae, that is, of those forms which eventually 
enter the sheep. Before the work can be regarded as com- 
pleted, we must trace the cercariae from the redia?, and determine 
the form and manner in which they enter the sheep, whether 
filum, M. Jala, l}i>>toma metjastoiiium, 1). ttvtiicoUe, 1). ococaudattiin, D. per- 
latuni, D. mcutulatuiii, 1). variegatum, D. cylindraoetim, Gasterostoma crucihulum, 
G. Jiinhriatum. 
* • Deir Adattftniento delle specie all' ambiente. Sremorio dell' Accademia 
(Idle Scicnze dell' Islitulo di Bologna.' Serio iv., tome ii., 1S8I. 
t ' Archiv fiir N;iturgcschicbte,' l!;82, p. SO. 
