184 Harry Lewis Wieman. 



study, for which purpose the material is much less favorable than 

 signaticollis. With the conditions in the latter relatively clear to 

 guide me, I am convinced that the odd body does not divide in 

 the first division in decemlineata. Telophases like those shown 

 in Figs. 62 and 64 would seem to settle this point very definitely. 

 Furthermore, the accessory body even in the late telophases does 

 not mingle with the ordinary chromosomes but occupies a position 

 at one side. If a separation of the components occurred, one would 

 expect both parts to behave similarly in this regard and remain 

 apart from the other chromosomes at their respective poles, but 

 such is not the case. At only one pole is an eccentric body to be 

 found and this bears an unmistakable resemblance to the nucleolus 

 of the resting stage (Figs. 64, 66). 



If, with Stevens, we regard the unequal pair as made up of two 

 somatic chromosomes, it follows that the equal pair of signati- 

 collis is likewise equivalent to two chromosomes. In this event 

 the spermatogonial number is thirty-four (2x16+2). 



The evidence from signaticollis would perhaps favor the idea 

 that the bi-partite body represents a single chromosome, since 

 its appearance and behavior in the maturation divisions recalls 

 the unpaired accessory of the Orthoptera and certain Hemiptera. 

 On the other hand, the fact that in decemlineata the homologous 

 components are of unequal size practically compels one to regard 

 the accessory body as two chromosomes in both cases. The 

 chromatin nucleolus of the ovocyte of decemlineata is composed 

 of two parts of unequal size (Fig. 65). 



It has already been pointed out that the odd body in all prob- 

 ability divides in the second spermatocytic division, but whether 

 transversely or longitudinally can not be readily determined. At 

 first I was inclined to believe that the division took place so as 

 to separate entire chromosomes but this view leads to serious 

 difficulties, since it would follow that three classes of spermatozoa 

 would be produced. In signaticollis one-half of the total number 

 would contain sixteen chromosomes; one-fourth of the total 

 number, sixteen plus one component of the odd body ; the other 

 fourth, sixteen plus the other component of the odd body. 

 The same kind of difficulty would be met with in decemlineata. 



