24 THE INFANCY OF ANIMALS 



less important in this connection : to wit, that a longer 

 time is required by a large animal than a small one to 

 attain maturity, and consequently the reproductive period 

 must be proportionately extended to ensure that a sufficient 

 number of individuals shall survive to reproduce in their 

 turn. It does not follow, however, that small animals 

 are of necessity short-lived, for the pike and the carp 

 are said to live a hundred years, a sea-anemone fifty 

 years, a cray-fish twenty years. 



But we are concerned now solely with the duration of 

 life in the mammals and the bearing thereof on the pre- 

 nascent period. Whenever this covers any appreciable 

 length of time, from many days to many months, the 

 young display features peculiar to this time. It must 

 be remembered that they are developing mentally as 

 well as physically. During this stage, then, they undergo 

 a more or less extensive education to fit them for the 

 strenuous life before them. Not the least important part 

 of this education is the requirement of rapid co-ordination 

 of movement ; and especially of those movements on 

 the accurate performance of which life itself may, even 

 in the near future, depend. 



A part of this education appears to be spontaneous, or 

 instinctive — as for example the gambollings of lambs, 

 and the play of kittens and puppies. At any rate, in 

 these things they seem to receive no direct instruction 

 from the parents : they do not, in other words, play by 

 imitating the actions of their elders. The nature of this 

 play is, as we have just remarked, the mirror image of 

 some of the most critical moments of the life before them. 

 The gambollings of the lamb are unconscious anticipations 

 of a race for life with wolves ; the play of the kitten 

 reproduces all the movements which will be necessary for 



