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but posteriorly continued into a short and wide oviduct, which 
terminates behind the vent, and mostly before the urethra. 
The inside of these sacs is more or less lined with the stroma, 
or a peculiar tissue, within which the ova are developed. In 
those forms in which the ova are hatched, before extrusion, the 
stroma does not extend to the hind portion of these sacs, for 
this locality serves as a sort of uterus, and is furnished while 
internal incubation is going on with a large albuminous 
secretion. The products of the reproductive organs may be 
set free in the peritoneal cavity, finding their exit at the 
abdominal pore or pores. Or these products may be taken up 
by the open mouths of the fallopian tubes, or distinct tubes 
conduct them all the way to their outlet. 
The various modifications of the generative organs in true 
fishes are a simple testis or ovary, but no excretory duct; a 
_ partial oviduct united to the ureter, but not continuous with 
_ the ovary; or a testis having a long and complex duct 
distinct from the ureter. Among Teleostean fishes breeding 
occurs in one of the following ways :—1. The eggs are hatched 
within the female organs, as seen in the oviparous blenny. 2. 
Asin the majority of these fishes, the eggs having been ex- 
cluded, are subsequently fertilised by the male, the milt or 
spermatozoa of the latter being brought into contact in the 
water with the ova or eggs of the female, when this microscopic 
body (the spermatozoon) obtains access by a minute orifice, 
termed the micropyle, into the interior of the ovum. In short 
_ in the breeding of osseous fishes the generative organs perform 
the following functions :—“ Semination,” “ ovulation,” “ fecun- 
dation,” and “exclusion,” to which in some forms is added 
that of “ foetation.” : 
_- Simple as this process would seem to be, there are many 
interesting questions about it which are still unsolved and 
quire attention. If all fishes’ eggs were of one size, the 
micropyle and spermatozoids identical in all forms, the specific 
gravity of all ova without variation, and all kinds of fish 
propagated their species at the same period we should soon 
arrive at a state of inextricable confusion. There would be 
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