564 
DR. MARTIN BARRY’S RESEARCHES IN EMBRYOLOGY. 
bule. In less developed cytoblasts there is observed only the outer sharp contour of 
this ring, and in its middle an opake point.***In cytoblasts still smaller, it appears 
only as a sharply circumscribed spot ; which is most frequently the case.***Or finally 
there is seen only a remarkable, minute, opake point. In the very smallest and most 
transitory cytoblasts I have not hitherto been able to detect it'f'.” — “From my ob- 
servations in all plants which admitted of a complete tracing of the whole formative 
process, it follows that this minute body forms even earlier than the cytoblast.*** 
The size of this corpuscle also varies considerably, from the extent of half the diameter 
of the cytoblast to points immeasurably small. ***Sometimes it appears more opake, 
sometimes more pellucid than the rest of the substance of the cytoblast. For the 
most part it is more consistent than the latter, and remains still sharply circumscribed, 
when this by pressure has become changed into an amorphous mucus “As soon 
as the cytoblasts have attained their full size there rises upon them a fine, transparent 
vesicle. This is the young cell, which at first presents a very flat segment of a sphere, 
the plane side of which is formed by the cytoblast, and its convex side by the young 
cell which is situated on it, somewhat like a watch-glass on a watch. ***Gradually 
now the entire cell grows out over the margin of the cytoblast, and speedily becomes 
so large, that at last the latter appears only as a minute body inclosed in one of the 
walls of the cell,***in which situation it accompanies through the whole vital process 
the cell which it has formed, if it be not (as in cells destined for higher development) 
either absorbed in its original situation, or — after having been cast off* as a useless 
member — dissolved and absorbed in the cavity of the cell. — The formation of second- 
ary deposits on the inner surface of the cell-wall does not commence, so far as I could 
observe, until after the absorption of the cytoblast §.” “A cell never shows a trace 
of a spiral formation***until full-grown, that is, until it has absorbed the cytoblast||.” 
“ The [spiral] fibres never form free, but in the interior of cells ; and the walls of these 
cells in an early state are simple and for the most part very delicate ^[.” 
426. Ova found in the Fallopian Tube and Uterus of the Rabbit. 
The two following Tables are a continuation of those given in the “ Second Series;” 
the object being, as then, to facilitate the discovery of the minuter ova in the Rabbit, 
by affording a general idea of their locality and size at different periods. They also 
serve to show that in both of these respects the ova of different individuals are sub- 
ject to variation ; — that there frequently exist considerable differences in the size and 
condition of ova destined to constitute the same litter of young ; — and that there is 
no fixed relation between the degree of development of ova and their size, locality, 
or age. 
t Beitriige, &c., Muller’s Archiv, 1838, Heft II. p. 141. % L. c., pp. 141. 142. 
§ L. c., pp. 145. 146. || L. c., p. 150. 5F L. c., p. 153. 
