SPERMATIC PARTICLES. 39 



segmented cells, or are they the ultimate product of a granular mass produced b_y the 

 liquefaction of these divided cells ? The presence in the field of pyriform moving 

 cells, of about the size of the subdivided ones, would certainly favor the former view, 

 as these were probably cells in a state of transition. On the other hand, the presence 

 of a fasciculus of these bodies in a parent vesicle would favor another mode of devel- 

 opment, if the fasciculi are the result of development, and not of a subsequent grouping, 

 as some have supposed.* This point I shall have occasion to refer to at another 

 time. The grand fact of vitalization has here been seen more distinctly than in the 

 other classes. 



3d. Aves. — The spermatic particles of birds resemble quite closely, as to their form 

 and other gross characteristics, those of reptiles. As they were the animals on which 

 the first exact observations of the genesis of these bodies were made,t more observations 

 have subsequently been made upon this than upon any other class, and those of a vast 

 number of genera have been delineated. 



My own observations have been made for the most part upon Passerince and Co- 

 liimbidce, and, as there is a singular uniformity throughout the whole class as to genesis, 

 those of these orders are good representatives of the whole. Exactly as in the pre- 

 ceding class, the sperm-cells appear on the inside of the testicular tubes among the 

 normal epithelial cells. Segmentation here goes on as previously described, and in place 

 of the crowded vitelline cells we have a fasciculus of spermatic particles. These, when 

 inside the parent vesicle, are never, as far as I have seen, very numerous, but appear to 

 bear a pretty close ratio with the number of segmented cells that the vesicle would 

 contain. This fact will admit of two constructions; namely, either that each of these 

 segmented cells was changed into a spermatic particle, and that, therefore, the fascicular 

 form was from a subsequent arrangement ; or, according to both Kolliker and Wagner, 

 that each of these served as a " cell of development," in which a single spermatic 

 particle was formed. The latter view is most supported by direct observation ; in fact, 

 I have never been able to see any condition looking at all like a stage of transition from 

 a cell to a spermatic particle ; but notwithstanding this, I should much hesitate offering 

 any decided opinion. The appearance of these bodies in fasciculi, as though they might 

 have been thus formed out of a solid mass, merits our attention here, because Kolliker 

 has based this type of genesis on observations of this class. 



According to Kolliker, there is formed inside the parent vesicle a granular mass, 



* Vid. Longet, Traiti de Physiologie, {De la Generation,) p. 114. 



t Wagner's Hisloire de la Generation et da Decelojrpement, etc., p. 26. Bruxelles, 1841. 



