528 Theophilus s. Painter, 



studied has been on the outside of the general circle of autosomes 

 during the maturation period. This is true of the somatic divisions 

 also. The fact may be explained in the following w^y. The accessory 

 chromosomes of all spiders divide or pass earlier to one pole than 

 the autosomes, and it is easy to imagine how the division would be 

 upset if the accessory chromosomes lay in the midst of the autosomes. 

 On the outside of the circle of autosomes, the accessory can pass 

 at any time to one pole without disturbing the rest of the chromo- 

 somes. 



MoNTGOMEEY described the accessory chromosome of Lycosa inso- 

 pita as arising from two spermatogonial chromosomes and Wallace 

 has found the same true in Agalena naevia. The observations 

 made on Maevia vittata are in accord with the results of these two 

 authors. 



C t e 1 s m e s. 



The origin of the ctetosomes is to be found in the two small 

 bodies shown in Fig. 4. It has not been determined how these 

 chromosomes behave during the earlier divisions, but the fact that 

 they are separate during the last spermatogonial division would 

 seem to indicate that they remain separate during the somatic 

 mitoses. 



The ctetosomes lag behind in the spindle of the last spermato- 

 gonial division and pass undivided to one pole or the other, simply 

 by a matter of chance as far as it has been possible to observe. 

 As a result the primary spermatocyte cells are of two classes; cells 

 which carry the ctetosomes, and tliose which lack them. While the 

 later behavior of the ctetosomes bears out these conclusions, several 

 other possibilities have not been overlooked. Among these, it was 

 thought that a regular division of the ctetosomes had taken place; 

 but while one pair went to its pole in an orthodox manner, the 

 other pair lagged behind in the spindle. In this case all the primary 

 spermatocytes should contain the ctetosomes, or, if we grant the 

 possibility that the pair which lags behind may pass to either pole, 

 then we should expect to find cells which lack tliese bodies and 

 cells which contain four ctetosomes. No basis for this possibility 

 has been found in a study of the later pei'iod. All the evidence of 

 the first spermatocyte division confirms the observations made during 

 the spermatogonial division. 



