SPERMATOGENESIS OF LICE 659 



experienced no difficulty in making an accurate count of the 

 chromosomes, and, as we stated, the frequency with which 

 we were al)le to make these counts can leave no doubt as to the 

 actual number of chromosomes. No evidence was found of an 

 unequal pair. The sizes of the chromosomes varied somewhat 

 and this, combined with their smallness, would have made it 

 possible to postulate dimorphism in the chromosomes only if 

 the difference in size were very marked. 



The tliird difference between the two accounts, namely that 

 referring to the unequal spermatocyte division, is the most 

 important. Miss Foot maintains that the first spermatocyte 

 chromosomes of Pediculus are very similar to those of 

 Euschistus, and states that as the first spermatocyte chromo- 

 somes ' have the same morphological characteristics as the 

 corresponding stages in other species of Hemiptera, it is logical 

 to assume that the second spermatocyte chromosomes would 

 be equally typical \ Unfortunately the paper is not illustrated 

 by the usual excellent photographs which characterize so many 

 of Miss Foot's works, and it is difficult to compare her Pediculus 

 figures with her series of photographs of spermatocyte divisions 

 of Euschistus. However, by comparing our preparations of 

 Pediculus with Miss, Foot's Euschistus photographs I have to 

 confess that I cannot see any resemblance at all. 



Further, Miss Foot's observations were made on smear 

 preparations. In such preparations I think one may say that 

 it is highly probable that spermatocytes dividing in such an 

 unequal manner as we described would be so distorted, if not 

 completely collapsed, as to be unrecognizable. The small polar 

 body-like cell which is given off from the spermatocyte is, 

 at the moment of its formation, a long finger-like process. In 

 a smear preparation it is most probable that this attenuated 

 process would be either torn away from the remainder of the 

 dividing cell or else the whole cell on being freed from the 

 surrounding cells would round itself off and appear as a cell 

 in equal mitosis. 



Sections of the testis of Pediculus show an orderly sequence 

 of stages from the spermatogonia at the free end to the fully 



