454 Exijerimenfs of the Devehpment of the Liver-Fluke. 
divisions reaching to the end of the body, but not showing any 
of the numerous branches so characteristic of the adult. Around 
each cercaria and germ is a loose delicate pellicle. 
The rediae containing the cercariae still shows the characteristic 
ring running round the body a little behind the pharynx, and at 
the hind end are still visible the two short lateral processes, 
now, however, more stumpy than in the younger redia?. The 
digestive tract was short, being only "24 mm. long in a redia of 
four times the length. 
There can bs no doubt that the cercaria^ I found really belong 
to the liver-fiuke. The rediae in which they occurred were 
closely similar to those I have found throughout in the exami- 
nation of the snails I have infected with embryos, and in the 
same snail with these rediae was a sporocyst, still recognisable 
by the eye-spots and papilla as belonging to F. hepatica. JNIore- 
over, all the specimens of L. truncatulus which 1 infected have 
proved to contain larval trematodes, clearly belonging to one 
and the same zoological species, and as a preliminary precau- 
tion a number of snails of the same gathering as those submitted 
to infection were examined, and all were completely free from 
larval trematodes. 
In the same snail I found also rediae producing not cercariae 
but other rediae, which we may term daughter-rediae. Indeed I 
have not been able to prove as yet whether the rediae forming 
the second generation in the series of forms belonging to the 
liver-fluke ever produce cercariae. In many cases, at any rate, 
the cercariae only appear as the fourth generation, and it may be 
that this is always the case. The rediae generating rediae appear 
to have a larger pharynx and intestine, and to contain fewer 
germs than those ])roducing cercariae. I saw as many as three 
well-formed rediae in a single parent-redia in addition to several 
smaller germs. The ring behind the pharynx is well-developed, 
iind in one parent-redia I found it so large that the diameter of 
the body was nearly doubled at this point. 
I reserve further details as to the structure of the cercaria and 
redia for a subsequent paper. I may, however, mention that the 
•existence of as many as four generations gives rise to a great 
increase in number whilst witliin the snail ; so that a single 
ifluke-egg may well give rise to over 1000 cercari;r. 
The one point remaining that I have still to elucidate is the 
■manner in which the cercariae are transferred to the sheep, and 
this I hope very soon to accomplish. This may be effected 
either by the sheep eating the mollusc containing the cercariae, 
or the cercariae may pass out of the snail and encyst upon 
grass, &c. The presence of a tail is certainly in favour of the latter 
view. Leuckart is inclined to believe that the larval flukes are 
