869 



section of the muscle fibers. As with the length of the muscle in 

 general also varies the length of ils fibers ^), and accordingly tlie 

 average number of them remains the saine, it may be assumed that 

 tilt' (ivera</e mimbev of the muscle fibers of man is the same 

 as that of iroman. This is then also valid for the number of the 

 motor nerve fibers, and also of all other nerve fibers and of the 

 neurones. 



Thus the ratio of the l)rain weights can only be determined by 

 the length and the area of section of the nerve fibers, or one of 

 them (not by the number). The volume of the cell-bodies is minute 

 in comparison with that of the other components of the neurones. 

 Now the brain weights are to each other in the same ratio as the 

 length of the nerve fibers, from which follows that the area of 

 section of the nerve fibers, i-eniains the same, just as between indi- 

 viduals of equal sex of a species. Between homoneuric species, on 

 the other hand, the area of section of the nerve fibers varies 

 proportionally to po-28. 



Hence there is no difference in the sexes as regards the physio- 

 logical i-elation between the muscular system and the nervous system. 

 For the human species, however, and certainly also for many, if 

 not for all Monkeys, tlie male sex does agree with the males of 

 other species, but the female sex does not, as far as relation between 

 these two systems of organs and the bulk of the body is concerned. 

 Dynamically, woman, in as much as she has to move a dispropor- 

 tionally greater body weight for her strength, is inferior to man. 

 The i-atio of the body weights is regulated here so, as woman pos- 

 sesses disproportionally less muscle, that the dynamic disadvantage 

 of the large individuals as against the small ones, is cancelled for 

 man as against woman, which requires squaring of the common 

 ratio of the brain weight and the muscle weight to the body weight. 



Thus it is not only for the human species, but also for other 

 Primates. The peculiarity existing here: slighter mobility of woman, 

 and on the other hand great mobility of man can only be accounted 

 for by the very special and contrary mechanic requirements which, 

 in this order, maternal care imposes on one, and family life on the 

 other sex. It is needless to point out the significance which this has 

 also in a sociological respect, and to demonstrate the impossibility 

 that we shall ever be justified in saying: "nous avons change tout 

 cela". 



') Gf. : R. Mayeda, Ueber die Kalibeiverhaltnisse der quergestreiften Miiskel- 

 fasern. Zeitschrift fur Biologie (Kühne und Voit), Band 27. (1890), p. 142 and li6. 



