Zoology. 283 
mately find their complete exhibition are developed, or even when they 
are never developed. Let me therefore add that if careful embryologi- 
be no reason why the ovarian cell of a bird should: not produce a mam- 
mal as well asa bird. But these relations are not equally clearly un- 
derstood by all; and some whose attainments should have led them to 
think differently, have so failed in their appreciation of them that they 
have regarded the ovum as simply an organic molecule, thus putting 
an end to all dispute in their own minds, as to spontaneous generation 
connection. : 
I W ate ryology is to the female, that spermatology is to the male. 
na histological point of view, the process is the same in each sex. in 
e one, you have a simple cell passing on in development toa new 
stat ; in the other, you have a simple cell passing on to the development 
ne of t xes; while in spermatology it is the result of one 
herefore, our philosophical studies in the latter begin for the most 
" the former they have ended; for the spermatic particle 
, the growth of which 
ompound mass, the parent 
Sperm-cell, in which, by a modification of its contents, are developed 
the spermatic particles. These organic particles are the true and only 
mals, where often there is a dissimilarity of form and external appear- 
her; and too often, too, do we see in the same 
e. Now, experiment has shown that, in 
