38 Edmund B. Wilson 



III. Though I have found it convenient to consider the two 

 foregoing interpretations separately, they evidently have many 

 points of agreement, and perhaps may be reduced to a common 

 basis. Both assign to the differential chromosomes a specific 

 function in sex-production, both recognize the possibility of a 

 determination of sex (as opposed to its transmission), by con- 

 ditions external to the chromosome-groups, and both assume, 

 in one sex, a specific difference in the sex-chromosomes, followed 

 by a Mendelian disjunction in the formation of the gametes. 

 The essential point in which the second interpretation diverges 

 from the first is that the sex-chromosomes are not conceived as 

 bearing the male or female qualities respectively but as differing 

 only in the degree of their activity, and this difference is assumed 

 to exist in the male only (owing to the relation of fertilization 

 to sex-production). It must be admitted that each interpreta- 

 tion involves a considerable element of pure conjecture, and that 

 each includes assumptions which without additional data must 

 be considered as serious difficulties. The principal one involved 

 in the first interpretation is the assumption of selective fertiliza- 

 tion; but if this assumption be granted I believe that it may give 

 an adequate solution of the problem of sex-production in the sexual 

 reproduction of dioecious organisms. The second interpreta- 

 tion avoids this difficulty; it may explain the primary difference 

 between the gametes of the two sexes, the latency of female 

 characters in the male, and the development of such secondary 

 female characters as may be regarded as an exaggeration or inten- 

 sification of corresponding characters in the male. It seems con- 

 spicuously to fail to explain the reverse case of characters that 

 are more highly developed in the male; and to many this will 

 doubtless appear a fatal difficulty. But we are still ignorant of 

 the action and reaction of the chromosomes on the cytoplasm and 

 on one another, and have but a vague speculative notion of the 

 relations that determine patency and latency in development. 

 Additional data will therefore be required, I think, to show 

 whether the difficulty in question is a fatal one, and in what meas- 

 ure either of the two general interpretations that have been con- 

 sidered may approach the truth. The positive result of the 



