94 HUMAN FECUNDITY 



feasts " may not improbably be the modern representatives of 

 these ancient customs in our own country.' x 



This evidence all points to a former condition when conceptions 

 could only take place at one season of the year. We must suppose 

 that it has gradually become possible for copulation to be followed 

 by conception at any period, and that therefore fecundity has 

 increased. 2 Some light is thrown upon the causes that underlie 

 these changes by a reference to certain facts regarding other 

 species. Before we turn to this question reference may be made 

 to the phenomenon of * mittelschmerz ' or intermenstrual pain. 

 It is not uncommon and is sometimes accompanied by a discharge. 

 The interpretation of this phenomenon is doubtful. One explana- 

 tion, however, has some interest for us. It is suggested that it may 

 represent the first steps in the establishment of a different variety 

 of sexual cycle in which the dioestrous periods occur fortnightly 

 instead of monthly. If this interpretation is correct, it would 

 mean that the sexual cycle is evolving in the direction of still 

 greater fecundity. 3 



6. It has frequently been observed that when members of a wild 

 species are brought into captivity there is a change in the sexual 

 season. This change may be in the direction of an increase or of 

 a decrease in the generative power. If the bringing into captivity 

 involves such an alteration of conditions as to disorganize the 

 generative process, then a decrease in fecundity may result. It 

 frequently happens, for instance, that carnivores are infertile in 

 captivity, and this may be due among other things to the absence 

 of fresh meat. 4 Generally speaking, however, if the alterations do 

 not produce disorganization, an increase in fecundity results, and 

 as there is no reason to suppose that the change in human circum- 

 stances was ever of such a nature as to produce disorganization, 

 we must suppose, on the analogy of what happens among other 

 mammalian species, that, if the betterment of the conditions has 

 had any effect, it has been in the direction of an increase in 

 fecundity. 



A few examples of what is meant may be given. The wild dog of 

 South America, the wolf, and the fox breed only once a year under 



1 Heape, loc. cit., p. 34. It may also be observed that among certain 



primitive races the menstrual flow is said only to occur at long intervals (Heape, 

 loc. cit., p. 30). Among Eskimo women there is said to be no menstruation in 

 winter (ibid.,*p. 29). For further details see Groom, Trans. Edin. Obst&t. 



Soc., vol. xxi, 1896 ; Havelock Ellis, loc. cit., vol. i, p. 90 ; Marshall, loc. cit., 

 p. 65 ; and Kelly, loc. cit., ch. v. * Heape, loc. CJt., p. 15. 



