THE ACCESSORY CHROMOSOME. 73 



normally in about equal proportions, it should be present in half 

 the mature germ cells of the sex that bears it. (d} Such dis- 

 position of the element in the two forms of germ cells, paternal 

 and maternal, should be made as to admit of the readiest re- 

 sponse to the demands of environment regarding the proportion 

 of the sexes, (e) It should show variations in structure in accor- 

 dance with the variations of sex potentiality observable in dif- 

 ferent species. (/) In parthenogenesis its function would be 

 assumed by the elements of a certain polar body. It is con- 

 ceivable, in this regard, that another form of polar body might 

 function as the non-determinant bearing germ cell. 



(a) If we accept the theory that the chromatin is the bearer of 

 hereditary qualities, there could be little doubt regarding the 

 necessary chromosomic character of a sex determinant. Sex 

 being an elementary characteristic of protoplasm, it would be 

 firmly established in the hereditary basis along with metabolic 

 activity, irritability, etc., and if any argument were needed at all 

 it would be a general one, not concerned immediately with the 

 question under discussion, but with the broader one suggested. 

 It will therefore be assumed that the chromatin is this basis. 

 This being true, it will only be necessary to point out that the 

 work of a majority of investigators definitely proves that the ac- 

 cessory chromosome is a chromosome, and its standing in this 

 respect is established. 



(b) With regard to what would theoretically be required of a 

 chromosome whose function should be the determination of sex, 

 it is probable that almost every investigator would hold an 

 opinion differing in some respects from those entertained by others. 

 What I can suggest in this connection will therefore be merely 

 tentative and an expression of my own views. One thing, how- 

 ever, would seem to be necessary ; i. e., that the determinant 

 should exist in the cells until they are definitely established as 

 elements of either an ovary or of a testis. 



If it be that the production of male elements is a sign of kata- 

 bolic conditions, or, in other words, of those that make a greater 

 demand of energy expenditure upon the developing cell, then it 

 would seem most natural that the determinant should be for the 

 purpose of carrying the transformation beyond the production of 



