44G 
Second Report of Experiments on the 
organs of the snail. I have found them in the liver with their 
digestive tract containing the yellow remains of liver-cells. In 
fact, the injury they do to the snails in forcing their way 
through the tissues gives rise to a serious mortality among the 
molluscs, so that only a few of my snails have survived three 
weeks after infection. 
By the 23rd day the rediae have reached the length of '6 or 
.7 m. (see Fig. 5) ; and the germinal cells, 
increased in number by a proliferation of 
cells from the lining membrane of the body 
cavity, similar to that described in the 
begun 
to separate into 
In some of these germs 
the formation of 
are very active ; 
sporocyst, have 
spherical germs. 
1 observed evidence of 
a gastrula. The rediac 
and when the snail is examined they soon 
contract the body-walls ; but if observed 
at once, bridges or bridles of tissue com- 
posed of cells with their processes may 
be seen to cross the body-cavity in various 
directions. These I believe to be con- 
tractile. A little in front of the lateral 
processes of the rediae may be seen ciliated 
funnels arranged in groups, and of the 
same nature as those in the sporocyst. 
The spherical germs increase in size, 
and assume an oval or almost oblong shape, 
but I have not, at the time of writing, 
been able to trace their development. 
They may prove to be another genera- 
tion of rediae, or the cercariae which finally 
enter the sheep. I have still two snails 
alive which have been infected for nearly 
five weeks, and I hope on dissecting them 
to complete the cycle of forms belonging 
to the liver-fluke (see Addendum, p. 453), 
Two points which I was enabled to make 
out during these experiments have a bearing 
upon the development of other species of 
trematodes besides the liver-fluke. In the 
first place I found that the snails swallowed 
the eggs of the fluke contained in the aquaria 
in large numbers. I had already observed 
that various species of slugs devoured eggs* 
strewn on their food without injuring them. But in the case of 
A free redia (second goncration) 
of the Livcr-fluko with tlio 
contents fovming into germs 
of the third generation. M»g- 
nificd 230 diameters. 
♦ Journal of the Royal Agricultural Society, vol. xvii., p. 11. 
