CHROMOSOME COMPLEX OF SPERMATOCYTES. 



307 



Regarding the enumerations I would say that much confidence 

 is reposed in those of the spermatocyte elements, but that there 

 is less certainty attending the figures derived from the sperma- 

 togonia. This is due to the fact that the latter cells are relatively 

 small and the chromosomes very large, so that the elements are 

 not well separated and clear. There is no fusion of the chromo- 

 somes in the metaphase, but they are long and sinuous and their 

 limits hard to discern. 



In general, then, it was found that for the family the number of 

 chromosomes in the spermatogonia is 23 and in the first sperma- 

 tocyte 12. Exceptions were found in Hesperotettix which has 23 

 in the spermatogonia and 1 1 in the first spermatocyte ; and in 

 Mcnniria which has 23 in the spermatogonia and 10 in the first 

 spermatocyte. Careful study revealed the fact that the exceptions 

 are only apparent, and that the reason for the deviation from the 

 family character is due to unusual associations of the sperma- 

 togonial chromosomes in the spermatocytes. This is brought 

 about by the action of the accessory chromosome which here gives 

 further evidence of its highly important 

 character. It will be well to outline the 

 history of the chromosomes in these 

 genera separately and then refer to the 

 principles of association involved later. 



2. The Cliroinosomcs of Hesperotettix 

 spcciosns. 



It is not my intention to discuss the 

 whole group of chromosomes in this 

 species, but merely to give the history 

 of the most strongly marked element. 

 I hope subsequently to make a careful 

 detailed study of the germ cells of the 

 various species of this genus to establish 

 the relations of the entire complement of 

 chromosomes, but at present that is not possible. 



If we examine the spermatogonial mitoses of this species we 

 find that the chromosomes are of the usual rod-shape type, but 

 among them there occurs one that is peculiar in being bivalent 



FIG. I. Polar view of a 

 spermatogonium of Hesperotet- 

 tix speciosus (all the drawings 

 of this genus were made from 

 speciosus material) in meta- 

 phase, showing a tetrad " rti." 

 Not all the chromosomes are 

 drawn. 



