76 EDMUND B. WILSON 



ters and the more obvious internal features are concerned. Taken 

 by itself this case may seem to form a legitimate piece of evidence 

 against Boveri's theory. It cannot, howevei , be taken alone, but 

 must be viewed from the more general standpoint given by the 

 evidence as a whole. We are still too ignorant of the significance 

 of the " sex-chromosomes " to form an adequate opinion as to the 

 meaning of the Y-element. It may be in this case (as I earlier 

 suggested) a degenerating element, or may represent an excess of 

 a chromatin that is duplicated elsewhere in the chromosome- 

 group; but these and other speculative possibilites that suggest 

 themselves may well await the outcome of further study. 



Department of Zoology, Columbia University, December 23, 1909. 



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