ARTICLES 593 



is whether or not this equaUty can be destroyed before 

 maturity is reached. It is a debatable point, but the fact that 

 strains occur which bear an excess of one sex or the other has 

 to be accounted for, and this seems to be the simple explanation. 

 It is just possible that, for some obscure reason, the gametes of 

 the homozygous parent might in cases exercise a selective power 

 over the other gametes trying to fertilise them, but evidence 

 against this will be put forward later. There is other evidence 

 in favour of the theory of numerical inequality between the 

 mature X and Y gametes. Sometimes in experimental breeding 

 with Mendelian characteristics the most unexpected sequences 

 of anomalous ratios appear, and this can only be attributed to 

 abnormal gametic fluctuation. That the relative numbers of 

 the two types of gametes can be affected before reaching 

 maturity by a variety of factors is also pointed to by other 

 facts. The numbers of the sexes at birth are never quite equal 

 anywhere. There is nearly always some small inequality. In 

 some parts of the globe females preponderate, though in most 

 places males are in excess. This shows that environment has 

 a certain effect on the gametes. Race also appears to be a 

 factor in certain cases, because there is the very singular fact, 

 which, as far as the writer is aware, has never been explained, 

 that among the Jews, no matter in what part of the world they 

 may happen to be resident, there invariably occurs a much 

 greater normal excess of male births over female than is the case 

 with Christians. One other curious thing may be mentioned 

 in this connection, and that is that, during the recent war, the 

 ratio of male to female births throughout Europe rose in a steady 

 and persistent manner, which seemed to eliminate the possibility 

 of coincidence and chance ; and one can only assume that the 

 war was in some obscure way beneficial to the welfare of the 

 Y gametes. In conjunction with this is the very remarkable 

 fact that the fluctuation in the number of male births per i ,000 

 female during the last century follows almost exactly the rise 

 and fall in the economic price of food. Now, it is impossible 

 for sex to be altered by nutrition after conception, so one has 

 to conclude that higher economic prices, and, consequently, 

 more hardships, are capable of affecting the gametic ratios of 

 the heterozygous sex, and of altering it in favour of the gametes 

 with the male potentialities. 



It, therefore, appears a just assumption that external 

 conditions can influence the proportions of the sexes ; and, 

 therefore, there seems to be no reason why distinct male and 

 female-bearing strains should not occur and be persistent so long 

 as the exciting cause, be it organic and hereditary or causal 

 and due to environment, is present. 



Given the undoubted existence of strains showing abnormal 



