INDIVIDUALITY OF CHROMOSOMES. I I 



so it is difficult to fix the exact stage of development of the cell. 

 The chromosomes in most smear preparations were irregularly 

 distributed in the cell, yet a few showed them in a kind of equa- 

 torial plate. I can confirm what Sinety (28) has said about the 

 metaphase : " A parler rigoureusement le metaphase neiste pas 

 dans cette categoric de cellules " (first spermatocyte). In many 

 cells of first spermatocyte there is really not a metaphase, that 

 is, there is no stage in which all the chromosomes lie in one 

 plane at the equator of the spindle, but as some are entering 

 others have separated and are passing to the poles. This is 

 partly illustrated by Fig. 17, but others of my drawings which I 

 have not been able to put among these figures show this differ- 

 ence of arrival at the equatorial plate region very distinctly. 

 Some cells show a good metaphase (Fig. 14). 



Fig. 1 6 and 17 show the division of the ring which breaks into 

 two semicircles at the equatorial plane. Fig. 17 shows the //, or 

 v, shaped chromosomes described by so many writers in the ana- 

 phase of the first maturation division. 



The ordinary chromosomes in the semiresting stage were de- 

 scribed above while speaking of the accessory. 



Attention should be called to the difference of shape of the 

 chromosomes as they appear in Figs. 31 and 34 or 35. While 

 in the former we have the bent rods quite numerous, in the latter 

 they are mostly straight rods. The spermatogonia are curved 

 less than those in the second spermatocyte and more than those 

 of the spermatic!. 



COMPARISON OF RESULTS AND DISCUSSION OF LITERATURE. 



As indicated above Sinety (28) and McClung ( 1 8) have described 

 and discussed the behavior of the accessory chromosome in the 

 spermatocytes of the Orthoptera. Both papers appeared after 

 my own principal results were obtained. I can hence add inde- 

 pendent, confirmatory evidence of its failure to divide in the first 

 spermatocyte mitosis and its division in the second and the result- 

 ing distribution to only two of the four spermatids. I have not 

 been able to confirm McClung's observation of a spireme condi- 

 tion of the accessory in the growth period. 



From the observation of the peculiar L chromosome in G. 



