INFLUENCES DETERMINING SEX. 325 



to a scarcity of males, and in such a case more male larvae than usual 

 are produced ; while early fertilization, which is a sign of the abun- 

 dance of males, results, according to Huber, in an excess of female 

 births. 



Any influence which is equivalent to a lack of individuals of one 

 sex acts, according to Dtlring, to produce an excess of births of that 

 sex, although there may be an actual deficiency. 



Thus, when the queen-bee is restrained by confinement, or by the 

 lack of wings, from the nuptial flight, or when the seminal receptacle 

 has been removed by accident or by an operation, or when the con- 

 tained semen has been killed by frost or exhausted, only males are pro- 

 duced. 



Something of the same kind has been observed in man, and the 

 fact that a war, which carries most of the men away from their homes, 

 is followed by an unusually great number of male births, has been re- 

 corded by many observers. 



The second part of the paper, which will be found by far the most 

 interesting to the scientific student, treats of those influences which 

 act in the same way upon both parents, and the author's conclusion 

 may be summarized as follows : 



The power to regulate fertility according to the means of subsist- 

 ence would be of use to the organism, and since the female has gradu- 

 ally acquired, through division of labor, the function of providing the 

 material for the growth of the young, an excess of females is a condi- 

 tion of rapid multiplication. We might therefore expect, what we 

 actually find to be the case, that organisms have gradually acquired, 

 through natural selection, the power to produce an excess of females 

 in time of plenty, and in a season of scarcity of food an excess of 

 males. 



I think, however, that careful examination of the evidence which 

 During has brought together will show that he has stated his generali- 

 zation in too narrow terms, and I think his facts will prove the follow- 

 ing : A favorable environment causes an excess 0/ female births, and 

 an unfavorable environment an excess of male births. 



It is true that abundance or scarcity of food is one of the most im- 

 portant elements of that whole which makes up the envirojime^it of an 

 organism, and in most of the cases which During quotes it is the con- 

 trolling factor ; but he gives many cases, some of which will be noted 

 further, on, where a variation in other conditions of life has produced 

 the same effect, causing an excess of male births when unfavorable, 

 and an excess of female births when favorable. 



In the case of man, the conditions of life are so much under con- 

 trol that it is difficult to state just what constitutes a favorable envi- 

 ronment, but I think we may conclude that, as a general rule, an envi- 

 ronment which produces a high birth-rate is favorable, and vice versa. 

 Now, During gives many tables to show that, among mankind, the 



