THE RATE OF GROWTH 103 



as you know, are born in an exceedingly immature 

 state. They are blind, they are naked, they are al- 

 most incapable of definite movements, quite incapable 

 of locomotion, and are hardly more than little imper- 

 fect creatures lying in the nest and dependent utterly 

 upon the care of the mother, quite unable to do any- 

 thing for themselves except take the milk which is 

 their nourishment. They are indeed animals born in 

 a much less advanced stage than are the guinea-pigs, 

 which appear clothed with hair, having open eyes and 

 sight, and able to run about, although rather wobbly 

 the first day or two. Upon the screen we see this 

 interesting result demonstrated to us, that a male 

 rabbit, the fourth day after its birth, is able to add 

 over seventeen per cent, to its weight in one day. 

 From that the curve drops down, as you see, with 

 amazing rapidity, so that here at an age of twenty- 

 three days the rabbit is no longer able to add nearly 

 eighteen per cent, daily, but only a little over six. At 

 the end of two months from its birth, the growth 

 power of the rabbit has dropped to less than two per 

 cent., and at two months and a half it has dropped to 

 one. The drop in two and a half months has been 

 from nearly eighteen per cent, down to one per cent., 

 and the rest of the loss of one per cent, i-s extended 

 over the remaining growing period of the rabbit. 

 Could we have a more definite and certain demon- 

 stration of the fact that the decline is most rapid in 

 the young, most slow in the old ? It is not in this 

 case any more than in the others the one sex that 



