MORPHOGENESIS OF THE MAMMALIAN OVARY 347 



tlie attempts to analyse the mechanism of sex inheritance and 

 development. Upon the cytological side we have the inter- 

 pretations correlated with the large amount of work being done 

 at the present time upon the determination of sex and the chromo- 

 some pattern of the germ cells. This is not the place in which to 

 enter into a discussion of the complicated problem of the cytologi- 

 cal basis in the determination of sex. The careful and detailed 

 work on a number of forms, mainly invertebrate and chiefly 

 insects has, as is of course well known, established the existence 

 of an extra chromatin mass (heterochromosome) or chromosome 

 complex whose presence is correlated with the development of 

 the female sex. 



Upon the basis of this fact theoretical considerations have led 

 generally to the conclusion that the heterochromosome is the 

 conveyor of 'femaleness', being an embodiment of 'determiners' 

 of the female sexual characters, and that the female is homozj^gous 

 as regards sex characters, the male being heterozygous. The 

 presence of the heterochromosome in the higher vertebrates and 

 its significance in the determination of sex are in a far from satis- 

 factory condition at the present time. In the case of man, Guyer, 

 Guthertz and Winiwarter have described heterochromosomes, 

 but their descriptions do not mutually support one another and 

 hence there is considerable uncertainty as to what the facts may 

 be. Their observations, however, together with those of Jordan 

 on the opossum and bat, Newman and Patterson on the armadillo, 

 Stevens on the guinea pig, Vejowsky on the cat, indicate the pres- 

 ence in the male gametogenesisof an extra chromatin mass (hetero- 

 chromosome). Jordan, however, states that it is absent in the 

 spermatogenesis of mongoose, cat, squirrel, rabbit and pig. Wini- 

 warter and Sainmont have observed in the oogenesis of the cat a 

 body that they suggest may be a heterochromosome. The mor- 

 phological basis of fact is therefore still very scant. The state- 

 ment may be vouchsafed, furthermore, that the correlation of 

 this individual chromatin mass with the development of female 

 sexual characters or even with the determination of the female 

 sex is unproven. 



