ROBERTSON: THE CHROMOSOME COMPLEX. 285 



STRBCI.A ADMIRABIHS. 



fly apart at the distal end, as do the dyads of the other chro- 

 mosomes. This seems to indicate that the accessory was prob- 

 ably split like the ordinary chromosomes before entering the 

 metaphase. These cells are typical of whole cysts that may 

 be found showing the unequal distribution of the chromosomes 

 to the daughter-cells of the first spermatocytes, thus giving us 

 the two forms of the second spermatocytes. 



In polar views of the second spermatocyte metaphase (figs. 

 40 and 41) , half of the cells in a cyst show the twelve and half 

 the eleven dyads.* In these figures a good clew may be obtained 

 as to size relations, for the chromosomes lie spread out flat 

 in the plate, and since all of them are double rods of about the 

 same diameter their relative size is merely a question of length. 

 Of course the size of the accessory here, in comparison with 

 the other chromosomes, is just twice as great as the first sper- 

 matocyte, because all the chromosomes here except the acces- 

 sory are just one-half as large as they were in the preceding 

 mitosis. In figure 41, where there is no accessory, the relative 

 sizes cannot be mistaken. There are the three extremely large 

 members, Nos. 12, 11 and 10, the three small ones, Nos. 1, 2 

 and 3, and a series 4, 6, 7, 8 and 9 coming between these, 

 many of which are often indistinguishable from each other. 



In figures 42 to 45 we have anaphases of the second sper- 

 matocyte, showing the division of the dyads in the two kinds 

 of cells. Nos. 42 and 43 are complete cells, showing the divi- 

 sion of those that have eleven, and 44, 44a and 45 of those that 

 have twelve dyads.* A fragment of the lower halves of each 

 of the latter had to be sought in the next section, but there 

 was no doubt as to the number of chromosomes being twelve. 

 The accessory may be recognized in 44 and 45 by its somewhat 

 greater diameter and more intense staining propensities. In 

 conclusion, it may therefore be said that one-half of the sper- 

 matozoa receive eleven chromosomes plus the accessory and 

 the other half eleven and no accessory. 



COMPARISON OF SYRBULA ADMIRABILIS WITH SYRBULA 



ACUTICORNIS. 



The first point to be considered is in regard to the number 

 of chromosomes. In this acuticomis seems to be different 

 from the whole family Acrididse. So far, with a few excep- 

 tions, there has been recorded for the family twenty-three 



* The unnumbered elements in figures 41 and 45 are the result of ac- 

 cident in preparing the drawing. They are not present in the cells. 



