232 THE HUMAN SPECIES 



The Elephant bears offspring, singly, every 3 or 4 years 

 Camel ,, 2 



Mare i year 



Cow and deer i 



Sheep and goat i or 2 once or twice a year 



Cat 3-6 twice 



Bitch 4-10 



Pig 6-12 



Hare 2-5 twice or thrice a year 



Rabbit 4-7 5 or 8 times ,, 



Mouse 4-10 4 or 6 times 



Man ranks with the larger mammals in the infrequency of 

 bearing young. No reliable data exist as to the fertility of the 

 anthropoids. According to Leuckart, the, proportionate weight 

 of the offspring to the mother averages : 



In woman about one-fourteenth of the mother's weight 

 pigs one-half 



mice three times 



The age of fertility lasts 



In the mare till the 22nd-2/th year 

 cow 20th 



sheep 8th 



pig 6th-8th 



woman 45th 



In a man the procreative power seldom lasts beyond the 

 sixtieth year. 



VII. Nervous System. 



The progressive evolution of the nervous system from the 

 lower animals upwards displays from the physiological stand- 

 point, just as from the anatomical, a gradual increase in the 

 scope and differentiation of the functions. The primitive con- 

 dition of a general sensibility of the whole body surface rinding 

 expression in a reflex contractility is succeeded by the develop- 

 ment of definite nerve-fibres and ganglia composed of nerve- 

 cells which in their highest perfection constitute the brain, 

 spinal cord, peripheral-fibres and the cells of the vertebrate 

 nervous system. In this province a very marked general 



