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, /. 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 yj^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. 



