336 FERNANDUS PAYNE 



SO much larger, in fact, that it undoubtedly contains a larger 

 quantity of chromatin than the other three combined. In this 

 respect Pselliodes resembles Acholla multispinosa (Payne, '09 

 and '10). 



The paper of Delia Valle ('09) again brought to the surface the 

 question of the variation of the number of chromosomes within 

 a given species and individual. This paper has been ably dis- 



^ ^ A ••^ B • • ^ C 



••• ••• 



•: 



••• E •• F 



Fig. 3 Pselliodes cinctus Fabr. 4, oogonial division with thirty chromosomes; 

 B, spermatogonial division with twenty-eight chromosomes; C, first spermatocyte 

 division with sixteen chromosomes; D, side view of the second spermatocyte divi- 

 sion, showing the four idiochromosomes as a tetrad group in the middle and the 

 relative size of the four; E and F, metaphase plates of the second spermatocyte 

 division, E showing the three small idiochromosomes in one plane in the middle, 

 and F showing only the single large idiochromosome in the middle. X 2275. 



cussed by Montgomery ('10) and Wilson ('10). These authors, 

 while they admit Delia Valle has done a good service in collecting 

 a large amount of data against the prevalent notion of chromo- 

 somal constancy, believe he has been unjust in his criticisms and 

 that his evidence is insufficient for his sweeping conclusions. It 

 is not my intention to discuss any of these papers, but to describe 

 a case of apparent variation and give what I think to be its 

 explanation. 



