No. 524] CHROMOSOMES AND HEREDITY 495 



use of this term, I fear, prejudices tlie situation by the 

 very aptness of the application. It may be that X only 

 means more X, and that this is a factor in sex determina- 

 tion. The only criticism that I have to offer of this view 

 is that it ignores the Y element, and thereby makes the 

 male condition the result of the absence of something 

 which, if present, turns the embryo into a female. It 

 seems to me that there is no warrant for considering the 

 male in this sense a lacking female. The physiology and 

 the biology of the males offer much to contradict such a 

 view of his composition. I should also object to the 

 above conclusion on the general grounds that it refers 

 a particular character to a single chromosome. 



Can we meet these objections if we admit that when 

 the Y chromosome is absent the things that it stands for 

 are redistributed, or are present in the other chromo- 

 somes whether equally or unequally distributed there 

 need not be decided? Correspondingly, the materials of 

 the X chromosome may be supposed to be distributed 

 in part also to the other chromosomes. The production 

 of male or female will then be determined by the prepon- 

 derance of the amount of X or of Y in any given combi- 

 nation. 



The groups with an accessory represent from this 

 point of view an extreme form of distribution of the X 

 material ; while those with a Y show a like distribution 

 of the Y material, but in neither case need we imagine 

 all of this material present in a given chromosome, i. e., 

 in X or in Y. But this assumption also meets with 

 difficulties in another direction, for we should be obliged 

 to assume that the chromosomes carrying the Y element 

 pass to the opposite pole at one division from those bear- 

 ing the X element and we have as yet no evidence to sup- 

 port such a view. 



These are some of the difficulties of interpretation: 

 Science advances by carefully weighing all of the evi- 

 dence at her command. When a decision is not war- 

 ranted by the facts, experience teaches that it is wise to 

 suspend judgment, until the evidence can be put to fur- 



