851 



possible to compute wider averages; but besides for Man tliere exist 

 still few data. In 1907 Lapicque demonstrated ') that this exponent 

 of relation, between the two sexes of the human species, is equal 

 to that between homoneuric animal species of diflferent weight. 

 Among Europeans, man is on an average about 12 i{:ilograms 

 heavier than woman ; his average brain weight is about one and a 

 half hectograms more than that of woman. By taking the results of 

 all the authors into account, Lapicque arrives at the round values 

 66 and 54 kilograms for the average body weights, and 1360 and 

 1220 grams for the average brain weights of European men and 

 European women, to which an exponent of relation of 0.56 answers. 



A much smaller exponent of relation holds within each sex; the 

 brain weight varies 'much less considei-ably in comparison with the 

 body weight. Lapicque draws attention to the discontinuity from one 

 sex to the other, which thus appears. It had already been long 

 observed that equal mean brain weights did not correspond to 

 equal means of body height or of body weight of men on one side, 

 and women on the other side; we have, in fact, to do here with 

 two distinct series, like two species. The paradoxal character of this 

 view, Lapicque continues, disappears when it is thus formulated t 

 "dans le cas de dimorphisme sexuel la difference sexnelle doit être 

 traitée au point de vue mathéinatique comme uiie difference spéci- 

 fique" *). The difference in body weight between man and woman 

 he justly considers as a clear secondary sexual property. In the 

 biain weight there is now a difference of the same order, and 

 assuming the above reasoning to be correct "ces deux caractères 

 en réalité se ramèneraient a un seul, la difference de poids corporel ; 

 la difference de grandeur encéphalique ne serait qu'une con.séquence 

 harmonique" ''). 



On closer consideration I cannot concur with this last conclusion 

 of the distinguished French physiologist. If it were correct, if actually 

 one of the sexual properties in question were the necessary conse- 

 qnence of the other, we should find not only a mathematically 

 equal relation, but also a causally equal lelation between all di- 

 morphous sexes as between the homoneuric species, for which 



1) Louis Lapicque, Difference sexuelle du poids encéphalique dans l'espèce 

 humaine. Bulletins et Mémoires de la Société d'Anthropologie de Paris. Seance 

 du 6 juin 11)07. Paris 1908, p. 337—344. 



') Louis Lapicque, Comparaison du poids encéphalique entre les deux sexes de 

 l'espèce humaine. Gomptes rendus de la Société de Biologie de Paris. T. 63, 

 Séance du 9 novembre 1907, p. 434. 



») Ibid., p.. 746. 



