ON THE DEVELOPMENT OE BILHARZIA H7EMATOBIA. 749 
original statement, to the effect that et intra-chorional germs 
of trematodes offer no distinctive characters/’ must, therefore, 
in the present state of our knowledge, be accepted as a 
general conclusion admitting many exceptions. 
As regards the intimate structure of the embryo, I have 
further to observe that, shortly after the extrusion of the 
larvae from the shell, the hitherto loose globular particles of 
sarcode now coalesce, apparently as a preliminary step to¬ 
wards a subsequent differentiation into special organs, which 
are probably destined to become “nurses” (Figs, g , i). 
Within the head, we may sometimes notice two, and some¬ 
times three, pedunculated bodies presenting various appear¬ 
ances ; but, when three are present, one of them is constantly 
more conspicuous than the other two. This most prominent 
blind sac I suppose to represent the stomach of the larva in 
its future cercarian stage. Under the very perfect T \" objec¬ 
tive glass—employed by Professor Strieker, of Vienna, when 
he was in this country—I had an opportunity of examining 
these structures exhaustively; and in the cavity of the central 
blind sac 1 distinctly recognised numerous highly refracting 
granules, the diameter of which averaged not more than 
twoo' // * The rudimentary stomach is often traceable whilst 
the larva is still within the egg. It measures about m 
length, including the peduncle; and T T *, 0 Q " in breadth. The 
width of the narrow stalk does not exceed - 9 -^ 0 ". The other 
two stalked bodies appeared to me to have the character of 
the so-called lemnisci of Dujardin and others, being also occa¬ 
sionally well seen whilst the embryo is still within the egg. 
The varying appearances presented by these stalked blind 
sacs rendered it difficult to interpret their morphological and 
physiological significance with precision. If Dr. Harley’s 
observations be correct, two only of these bodies are con¬ 
stantly present, and communicate with the oral papilla by 
two distinct tubes and apertures. 1 regret that I have never 
had the good fortune to see these orifices; but I do not on 
that account doubt their presence. As regards the integu¬ 
ment, it is easy to recognise two layers, especially when the 
epidermis is unnaturally raised by endosmosis and injury. 
In careful adjustments of the focus, the inner wall of the 
transparent dermis presents a beaded appearance. Moreover, 
these minute and regular markings do not undergo the 
slightest alteration during the contractions of the body of the 
larva. In advanced embryos, the sarcodic masses also in¬ 
variably retained their general characters during contraction 
of the body. But, without dwelling further on such compa¬ 
ratively uninteresting matters, it yet remains for me to assert 
i 1 1 i . < i ' > * • « * » * * . .... 
