THE DETERMINATION OF SEX. 31 



may bear male blossoms before its proper female flowers. In Morus 

 nigra, and in other cases, according to Miller, male flowers may be 

 borne first, and afterwards fruit. Treviranus observed that the first 

 flowers of beech, chestnut, and other trees are male. Clausen gives 

 similar examples; and Hoffman notes that in the horse-chestnut, and 

 several other cases, male flowers appear first, and afterwards 

 hermaphrodites or females. 



Most of the results in regard to the influence of age are, however, 

 extremely unsatisfactory and conflicting. This is evident from the 

 above statistics. The law of Hofacker and Sadler can not be regarded 

 as in any sense established. In fact, as Hensen remarks, unless 

 statistics are enormously large they prove very little. The number of 

 other factors besides parental age which may operate in any case is 

 evidently great, — health, nutrition, frequency of sexual intercourse, 

 abstinence after the birth of a male, and the like, all reduce the 

 feasibility of the statistical method. At present, at any rate, we are 

 not justified in ascribing much importance to the relative age of the 

 parent except as a secondary factor, influential doubtless in relation to 

 nutrition. 



VII. Comparative Vigor. — The best known, and probably still 

 more influential, theory is that of "comparative vigor." As 

 elaborated by Girou and others, this hypothesis connects the sex of 

 the offspring with that of the more vigorous parent. It can not be 

 said, however, that facts bear out the case. Thus consumptive 

 mothers produce a great excess of daughters, while Girou' s theory 

 would lead us to expect the opposite. We require, in fact, to have 

 " vigor" analyzed out into its component factors, and in so doing we 

 shall afterwards find not only facts but reasons in favor of the 

 conclusion, in part included in the above theory, that highly 

 nourished females tend to produce female offspring. That form of 

 the hypothesis which refers the determination of sex to ' ' genital 

 superiority," or to "relative ardency," can hardly be seriously 

 considered. In this connection it has been maintained that in 

 "marriages of love," after a short bethrothal, female offspring 

 predominate; and a number of other interesting facts of a like nature 

 are suggested. Some skepticism as to the practicability of such 

 inductions is, however, inevitable. 



VIII. Starkweather's Law of Sex. — Closely allied to the 

 theory of comparative vigor is that elaborately worked out by Stark- 

 weather, which is suggestive enough to deserve separate summary. 

 He starts from a discussion of the alleged superiority of either sex. 

 Few maintain that the sexes are essentially equal, still fewer that the 

 females excel; the general bias of authority has been in favor of the 



