182 Harry Lewis Wieman. 



number to be twenty-two in both sexes. The fertilization form- 

 ula is: 



Egg 11 + s-pcrm 11 (10 + accessory) = oosperm 22 (cf or o). 



Gross complicated his conclusions by a very fanciful inter- 

 pretation of the relation between the accessory and the micro- 

 chromosomes, which I shall not enter into here. 



Wilson ('09a) confirmed Gross's observation that in Syromastes, 

 the spermatogonial number of chromosomes is twenty-two, and 

 that in the second maturation spindle there is a bivalent hetero- 

 tropic chromosome. He also pointed out that the bi-partite 

 nucleolus of the resting stage is composed of slightly unequal 

 parts. Since the accessory arises from two chromosomes, Wilson 

 considers it equivalent to two in the maturation divisions. There- 

 fore the number of chromosomes characteristic of the two classes 

 of spermatozoa are ten and twelve respectively, both classes 

 being assumed to be functional. In a later paper Wilson ('09c), 

 the ovogonial number was found to be twenty-four. The fertil- 

 ization formula is given as follows: 



Egg 12 + sperm 10 = oosperm 22 (cf ). 

 Egg 12 + sperm 12 = oosperm 24 (o). 



The fertilized egg then, contains two bivalent accessory chromo- 

 somes, which judging from the facts of the spermatogenesis one 

 would expect to appear in the resting stage of the ovocyte as a 

 quadri-partite or quadrivalent body. To determine this point in 

 L. signaticollis, I examined series of sections of young ovocytes, 

 and found shortly after the last ovogonial division, a stage ident- 

 ical with synizesis in the male in which there appears a bi-partite 

 basic staining nucleolus of approximately the same size and equal 

 in all respects to the body noted in the spermatocyte at a cor- 

 responding stage. This is represented in Fig. 39. In Fig. 40, the 

 spireme is unwound and is a stage that is comparable to Fig. 47 in 

 the spermatocyte. Figs. 41 and 42 are slightly older. In the latter 

 the nucleolus is seen at the end of the widely separated parts of 



