SEX DETERMINATION IN CATTLE. 223 



as is seen in the male. The same consideration applies to the 

 male and female germ cells. The ovum is much less widely 

 differentiated from the primordial indifferent germ cells than 

 is the spermatozoon. Now if it be assumed that two 'doses' 

 of this specific X-chromatin serve to inhibit completely the 

 development of ' maleness,' while one ' dose ' is insufficient to 

 do this, but allows the male characters to develop, we shall have, 

 it seems to me, a more satisfactory interpretation than is gained 

 by looking at the matter in the reverse way. 



"This viewpoint would explain why it is that castrated males 

 do not, save possibly in exceptional circumstances, take on 

 female characters. On the other hand, according to Goodale's 

 observations, castrated females do take on male characters. 

 Further an explanation is found for the numerous cases in which 

 a female in old age or after disease takes on male characters. 



"On this view hermaphroditism becomes analogous to the 

 phenomenon of the retention of larval characters in development 

 it being assumed that there is one 'dose' or less of J^-chromatin 

 in such cases." 



On either of these hypotheses as to the sex-determining action 

 of the ^-chromosomes it is not difficult to conceive how any 

 change in the general metabolic condition of the germ cells might 

 modify the sex ratio. The J'f-chromatin would presumably be 

 affected along with the rest of the cell and the relative potency 

 of its sex-determining factors changed. 



In conclusion we wish our position in regard to the results 

 set forth in this paper to be clearly understood. It is not con- 

 tended or supposed by the writers that the time of service in 

 relation to the period of heat absolutely controls the sex of the 

 subsequent offspring. It is believed, however, that the facts 

 set forth show, with a considerable degree of probability, that 

 the sex ratio in cattle can be to some extent modified by controlling 

 the time of service. But the amount of such observed modifica- 

 tion is not so great that the matter can be tested with a few 

 individuals. There is every reason to believe that any effect 

 would only appear in fairly comprehensive statistics. The matter 

 is one of much practical consequence to the stock breeder. 



Because this is so we would caution the reader against misinter- 



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