518 
A comparison of figures 21 and 22 would seem to indicate that 
a second numerical reduction or synapsis of chromosomes (hemioid 
group) does not occur in the bat, in which respect also it differs from 
man [GuYER!)] and opossum [JORDAN ”)]. 
Many of the spermatids contain a small central slightly chromatic 
nucleolus in their vesicular nucleus (fig. 23). This may be traced for 
a considerable period during the early stages in the formation of the 
sperm head. But the number containing this chromatic body seems 
clearly greater than half; and those lacking it in section may simply 
not have had included that portion of the cell containing it. The 
evidence strongly indicates that the body — which may very probably 
be the analogue of the accessory chromosome of other forms — noted 
during synapsis where it is characterized by certain peculiarities of 
Fig. 22. Metaphase plate of dividing secondary spermatocyte. 
Fig. 23. Spermatid, showing small nucleolus (plasmosome) in the vesicular 
nucleus, large idiozome and many spherical mitochondria. 
Fig. 24. Large interstitial cell, with small vesicular nucleus, and many oval 
mitochondria, dark brown in color. 
behavior, is no longer morphologically, nor by reason of unusual 
behavior, commonly distinguishable among the ordinary chromosomes. 
Hence there is no evidence for concluding that a specific morphological 
differentiation comparable to that of many forms, obtains in bat 
spermatozoa. This conclusion is strengthened, perhaps, by the ob- 
servation that the probable chromosome nucleolus of the young 
spermatocyte is frequently bipartite or even double; and it may pos- 
sibly divide like the ordinary chromosomes at mitosis; or like a pair 
of heterochromosomes. 
This, however, does not necessarily imply that there is no specific 
physiological differentiation. Indeed the fact that a certain chromo- 
1) Biol. Bull., Sept. 1910. 
2) Arch: f. Zellf., Bd. 7, 1911. 
