208 KANSAS UNIVERSITY SCIENCE BULLETIN. 



seems absurd to assume that the separation of an individual 

 chromosome by one plane could be quantitative while the sep- 

 aration by another plane was qualitative," is well founded. 

 At the basis of such an assumption lies the implication that 

 any definite arrangement of chromomeres is impossible ; for if 

 any definite order were possible, then the supposed argument 

 against the longitudinal disposition of the chromomeres would 

 be invalid. 



The argument of Wilcox is therefore directed against order 

 in general, and not against order in any one particular, as he 

 would have it appear. For it must be admitted that if it is 

 possible for the scattered chromatic granules of the early pro- 

 phase to arrange themselves at all (and this even Wilcox does 

 not deny) , it is equally possible for them to come together in a 

 definite order. That they do this is amply evidenced by the fact 

 that later they appear in definite groups or chromosomes. It is 

 to be noted, moreover, that the later investigations tend to sug- 

 gest that the apparently unorganized chromatic granules in the 

 first spermatocyte prophase are really bound together and rep- 

 resent merely a diffuse condition of the spermatogonial chro- 

 mosomes. 



Wilcox's chief error, however, is not to be sought in specu- 

 lative theories, but rather in his faulty observations. He 

 repeatedly denies the occurrence of any longitudinal split in 

 the chromatic thread of the first spermatocyte prophase. That 

 he is mistaken here I am thoroughly convinced, both from a 

 study of his own object and from investigations upon many 

 other species of the same family. At the present time, also, 

 practically every spermatologist is aligned in support of the 

 view denounced by Wilcox. For a while Wilcox had some 

 backing, but most of those who advocated only cross-divisions 

 •of the thread have later been able to demonstrate the longitu- 

 dinal cleavage in better prepared material. 



There is general acceptance of the opinion that the chromo- 

 meres of the last secondary spermatogonia appear in a linear 

 arrangement to form what is commonly known as the "spi- 

 reme." Wilcox declared that while in a very fine condition 

 this thread breaks across into segments, which unite by pairs 

 to form the chromosomes of the first spermatocyte. The great 

 majority of other investigators are unanimous in the opinion 



