Observatio7is on Young Mammals. 107 



in the immature kitten acquisition appears to be the chief 

 factor. 



A very interesting observation is that which Dr. Mills 

 summarizes as follows : "I have found, in the case of all 

 puppies, and several other kinds of animals examined 

 (the cat and the rabbit, for example), that even on the 

 first day of birth they will not creep off a surface on 

 which they rest if elevated some little distance above the 

 ground. "When they approach the edge they manifest 

 hesitation, grasp with their claws, or otherwise attempt to 

 prevent themselves falling, and it may be cry out, giving 

 evidence of some profound disturbance in their nervous 

 system." And he adds, " It is interesting to note that a 

 water-tortoise I have had for some years, will at any 

 time walk off a surface on which it is placed," and fall 

 to the ground. The newly born animals on which Dr. 

 Mills experimented were still blind, so that the effects 

 were not due to sight, but probably to the lack of support 

 experienced when the edge of the surface was reached ; 

 and they exemplify a very interesting mode of apparently 

 instinctive behaviour. Spalding's observation on a two- 

 days-old pig may be quoted for comparison. "When 

 placed on a chair, it knew the height to require considering, 

 went down on its knees, and leapt down." The expression 

 "knew the height to require considering" is unfortunate 

 and open to criticism. But the kneeling preparatory to 

 leaping down is a matter of direct observation, and not of 

 inference. Mr. Mann Jones, in a letter with which he 

 has favoured me, says, " The going down on the knees 

 (i.e. bending the wrist joint) is the ordinary resting position 

 in both young and old pigs, and the only inference war- 

 rantable from the action is that the muscles were tired 

 by standing. I doubt whether any mammal," he continues, 

 "ever 'leapt' from such a position. If the pig attempted 



