242 
DR. MARTIN BARRY ON THE CORPUSCLES OF THE BLOOD. 
gest variety in their particular mode of origin. But I have no reason to doubt that 
the foundation of spermatozoa in general consists of the objects I have denominated 
discs. 
187- The corkscrew-like spermatozoon of certain Birds has presented to me ap- 
pearances, which it seemed worth while to delineate (figs. 162, 163.) ; and I recom- 
mend that the description of these figures should be referred to ; leaving it, however, 
for the future to determine, whether the curious division of discs in a longitudinal 
direction, there suggested, really takes place. 
188. In a former page, I referred to a parent corpuscle (fig. 94. a) having the same 
appearance as the corpuscle of the blood, filled with young corpuscles, which had 
been destined to form epithelium-cells. I have now to mention that young corpus- 
cles are met with, while still within their parent cell, manifesting a very different 
destination. The cell in fig. 164. is a parent corpuscle having the appearance of an 
enlarged corpuscle of the blood ; and each of the contained objects is a young cor- 
puscle. But each of these young corpuscles is also a rudimental ovum. (Compare 
with the ovum in my First Series on Embryology, l. c., Plate V. fig. 19.) The objects 
also in fig. 165, though mere discs having the same appearance as blood-discs, are 
rudimental ova. Those in figs. 166, 167, 168, 169, — presenting the ovum in states 
somewhat more advanced, — are also altered corpuscles having the same appearance 
as corpuscles of the blood. Even the most forward of the objects now referred to, 
presented red colouring matter quite sufficient to show, to an eye accustomed to 
these investigations, from whence they arose. But besides this, they admitted of 
being traced back into corpuscles having the same appearance as corpuscles of the 
blood (figs. 164, 165.). And all the objects in question, it may be added, were from 
the ovary of the same individual Bird. 
189. The essential part of the ovum in these figures, is that marked c. It is the 
germinal vesicle : very much in advance, it will be observed, of other parts, in the 
degree of its development (see its large size in fig. 169. y); being, as I originally 
said, the first part of the ovum which is formed. Its progress admits of being traced, 
from merely a pellucid space — the centre of a corpuscle having the same appearance 
as a blood-corpuscle, fig. 165. a — through the discoid form, as in the centre of the 
corpuscle (3 — to the state of an incipient cell, as in y of this, and in some of the other 
figures. I have seen the future germinal vesicle, as a disc, measuring in diameter no 
more than y^th of a Paris line (figs. 164, 165.). 
190. The most essential part of the germinal vesicle, is seen in many of the figures 
which represent the latter. While the future germinal vesicle is a mere disc, its 
most essential part is the depression in the centre of the surface of this disc : and 
when the future germinal vesicle has really become somewhat vesicular in form, there 
is seen an orifice in the same situation (figs. 165 y, 166, 167-)- This orifice denotes 
the situation of the essential part of the germinal vesicle, — the future germinal spot. 
