314 PROCEEDINGS OF THE ACADEMY OF [April, 



Acronycta bp. 



A small cocoon found upon a Cecropia cocoon was identified b} r 

 Prof. John B. Smith of Rutger's College as an Acronycta, possibly 

 oblinita. By comparison with oblinita it was found that this was not 

 the species, but because of certain unusual structures in the cytoplasm 

 of both spermatocytes and spermatids it seemed of sufficient interest 

 to be included in the present study. This material was fixed with 

 the same care and by the same methods as were used for other forms 

 so that the si ructures here described cannot be the result of bad preser- 

 vation. 



The testes which in all the Saturnids remain paired are fused in 

 this form along the midline, suggesting a similar condition mentioned 

 for butterflies. In the rest stage of the first spermatocyte the nucleus 

 shows the usual deeply-staining nucleolus and a fine linin meshwork, 

 while in the cell cytoplasm beside the centrosomes a darkly-stained 

 body appcais (figs. 171 and 172); except for its greater size, this body 

 appears and behaves like the "chromatin granule-" described for the 

 family of Saturnids, and like them may be seen to divide and migrate 

 to opposite pole-; of the cell (figs. 17S and 170). In addition to this 

 an irregular mass is often found which in form and staining reaction 

 resembles chromatin and looks as though it had been thrown out of 

 the nucleus; though this suggests the Mitochondria of Benda (1899) 

 and similar bodies described by Meves (1902) and Schreiner (1906) 

 and is traceable in many cells throughout all stages, yet it was not 

 ^■eQM to take any part in cell development. In the cytoplasm in all 

 stages of prophage (figs. 173 and 174) both "chromatin granule" and 

 .Mitochondria are to lie seen: the former as divided and beginning to 

 migrate; the latter as an inert mass. In the first maturation division 

 (fig. 177) a partial division of the Mitochondria is seen, while figs. 

 176, 178 and 179 show various stages in the equal division of the 

 chromosomes and of the "chromatin granule." < )ne thing which is 

 very noticeable here in contrast to all other forms is the position of 

 the spindles which lie to one side of the cell, while the chromatin 

 granule and Mitochondria occupy the other side; an exception to this 

 is seen in fig. 176, where one of the "chromatin granules" is placed 

 upon the spindle. A metaphase of the second maturation division 

 shows, in addition to a chromatin granule and a Mitochondria twenty- 

 nine chromosomes. By an apparently equal division of the chromatin 

 granules each spermatid receives not only a nucleus and a nebenkern 

 from the mother cell, but also a "chromatin granule" surrounded by a 

 clear zone; this granule at first lies beside the nucleus of the spermatid, 



