THE HEREDITY OF SEX 65 



the statics of the cell rather than its dynamics. 

 Cytology is in fact a branch of anatomy, and in the 

 anatomy of the cell we have made some progress, 

 but our knowledge of the physiology of the cell is 

 still infinitesimal. The nucleus, and especially the 

 chromosomes, are supposed in some unknown way 

 to influence or govern the metabolism of the cyto- 

 plasm. From this point of view the hypothesis men- 

 tioned above that the sex-difference in the gametes 

 is not qualitative but quantitative is probably nearer 

 to the truth. Geddes and Thomson and others have 

 maintained that the sex-difference is one of meta- 

 bolism, the ovum being more anabolic, the sperm 

 more katabolic. A double quantity of special 

 chromatin may be the cause of the greater ana- 

 bolism of the ovum. In that case the difficulty 

 indicated in a previous part of this chapter, that the 

 ovum after reduction resembles the sperm in having 

 only one X chromosome, may be explained by the 

 fact that the growth of the ovum and its accumula- 

 tion of yolk substances has been already accomplished 

 under the influence of the two chromosomes before 

 reduction. Other difficulties previously discussed 

 also appear to be diminished if we adopt this point 

 of view. We need not regard maleness and female- 

 ness as unit characters in heredity of the same kind 

 as Mendelian characters of the soma. Instead of 

 saying that the zygote composed of ovum and 

 spermatozoon is incapable of giving rise in the male 

 to ova, or in the female to sperms, we should hold 

 that the gametocytes ultimately give rise to ova or 

 to sperms according to the metabolic processes set 

 up and maintained in them through their successive 

 cell-divisions under the influence of the double or 



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