ELEVENTH ANNUAL MEETING. 59 
Brooks has represented the freshly-laid ova of the oyster with 
a spherical nucleus and nucleolus; the former is large and 
clear, and is embedded near the center of the egg, and inside of 
it the nucleolus is lodged somewhat to one side. I do not find 
the latter spherical, as described, but formed as if composed of 
a larger and smaller highly refringent pair of spheres, partly 
fused with each other, or of the same form as the nucleoli of the 
eggs of Anodonta as described by Fleming, and somewhat simi- 
lar to those of the slipper limpet (Crepidula glauca) as observed 
by the writer. Some very singular figures of the eggs of the 
European oyster in Poli’s work, published in 1795, renders it 
not improbable that he may have seen this singularly-formed 
nucleolus, which seems to characterize to a certain extent the 
eggs of bivalves. 
The ova are not all ripe in all cases at the same time in the 
same ovarian follicle. The same condition of affairs is found 
in the ovary of the oyster as was observed in Scrobicularia by 
Von Jhering, that is, while some ova was mature, others in the 
same follicle were still, very immature. The condition of the 
ovary varies considerably in different individuals; in some cases 
the most of the ova are ripe at about the same time, in others 
there is a greater difference between the time of maturity of the 
different eggs of the same follicle. It is also frequently ob- 
served that a_portion of the generative organs of the same oyster 
are much more advanced toward maturity than others. It is 
also found that when the oyster is in its fullest spawning con- 
dition, the generative organ forms by far the greater proportion 
of the solid substance of the visceral mass lying between the 
heart space and the head and palps next the hinge; but the 
generative organs may be so undeveloped in winter as to form 
only a very small proportion of the substance of the visceral 
mass, and are present only as a fine reticulum or network of 
germinal cells. The ovaries and spermaries are therefore never 
entirely wasted away or atrophied, as would appear to the 
naked eye. : 
The full, engorged appearance which is noticed when the gen- 
erative glands are full of ripe products is often due to a disten- 
sion of the ducts which lead away from the follicles, and when 
