0)38 ON THE DEVELOPMENT OF BILtlARZIA IItEMATOBIA. 
as it was seven years ago. The difficulty lies, on the one 
hand, in my cases, in the almost complete concealment of 
the adult parasite—for as yet I have only seen fragments of 
the animal; and, on the other, in the imperfection and insuf¬ 
ficiency of the published figures of Distomum haematobium, 
together with the facts that both Bilharz and Griesinger 
describe and figure two forms of egg, the one with a terminal, 
and the other with a lateral spine. In all my own cases, I 
can say positively that only one form of egg has existed, 
namely, that with a terminal spine. Variation in the size, 
length, and outline of the egg is often observable; but I have 
never seen any egg w T ith even a tendency to the formation of 
a side spine. I even doubt whether this peculiar form exists 
in Distomum haematobium itself. To my mind, the objects 
represented appear to be escaped embryo masses, and not 
eggs. Griesinger himself speaks of them as eggs or cocoons. 
If these two talented observers yielded this point of differ¬ 
ence in the ova of the Egyptian parasite, then I grant 
that I find no difference between Distomum haematobium and 
Bilharzia capensisB 
It thus appears that Dr. John Harley would establish 
specific differentiation on slight, or, at all events, on more or 
less well marked variations of egg-contour. Further on, I 
hope to be able to. convince Dr. Harley that it is not neces¬ 
sary to refer this question to the savans above named ; and I 
almost doubt if he has, for himself, carefully looked into their 
writings, or to the abridged account of them given by Leuc- 
kart. So far from there being no good figures of the adult 
worm, it has always appeared to myself that LeuckarFs 
various representations are remarkably accurate and com¬ 
plete. In his first memoir, morever, Dr, Harley is singu¬ 
larly unhappy in his references to foreign authorities. Thus, 
in the Transactions for 1867, he says (page 62) : “ Bilharz 
and Griesinger, followed by Derseble [sic], Kuckenmeister 
[sic], and Leuchart [sic], have described this parasite. - ” Now, 
apart from the obvious misspelling of the names of Leuckart 
and Kiichenmeister—a carelessness shared by some other 
writers—the word Derseble is introduced, and made to do 
duty for a separate substantive authority. This spurious 
title Derseble is a misrepresentation of the German pronoun 
derselbe; and, when the original reference is consulted, it 
will be seen that the pronoun (= Idem, or the same author) 
clearly refers to a second contribution by some previously 
quoted authority. The writer really quoted by Leuckart, 
whence Dr. Harley has borrowed his references [Die Mens- 
chlichen Barasiten , s. 617), is Bilharz, who had contributed a 
