Germ Cells of Leptinotarsa Signaticollis. 181 



There is nothing of especial interest in the remaining details 

 of the spermatogenesis except one stage in the development of 

 the spermatozoan, where the head is seen to be made up of sharply 

 defined basic-staining spheres whose number I estimated to be 

 the same as the reduced number of chromosomes (Fig. 61). A 

 little later this configuration disappears, and the head of the 

 mature spermatozoan shows a smooth solid basic staining mass 

 of the usual pointed form characteristic of Coleoptera. 



As has already been mentioned the tangled condition of the 

 chromosomes in the spermatogonial plates makes a direct deter- 

 mination of the unreduced number almost impossible. However, 

 it is clear from the maturation spindles that the number must be 

 thirty three or thirty four, depending upon whether the odd 

 body is to be considered equivalent to one or two chromo- 

 somes. 



At this point, I should like to call attention to certain appear- 

 ances in the cytoplasm at the beginning of the growth period, 

 that are suggestive of a process comparable to yolk formation in 

 the ovocyte. As seen in sections, this consists of a crescentic acid- 

 staining area traversed by a coarse irregular fibrous network 

 (Fig. 49) that grows until it nearly fills the cytoplasm (Figs. 50, 

 and 51). When the nuclear membrane disappears for the first 

 maturation division, this material becomes diffused throughout 

 the entire cell and loses its distinctness. It is interesting that its 

 staining reaction is similar to that of the yolk of the egg. 



The appearance of the resting stage recalls at once the condition 

 first described by Gross ('04) in Syromastes marginatus, in which 

 he observed a bi-partite nucleolus that arises by the synapsis of 

 two spermatogonial chromosomes. This constitutes the accessory 

 chromosome which from its mode of origin is bivalent. It divides 

 longitudinally in the first division, but fails to divide in the second, 

 passing bodily to one pole in advance of all other chromosomes. 

 The result is that all of the spermatid nuclei receive ten chromo- 

 somes and half of them, in addition, the accessory. He further 

 supposed only those spermatozoa to be functional that contained 

 the accessory, the others being regarded as comparable to polar 

 bodies. From the numerical relations he believed the somatic 



