PERFECTION OF INSTINCT. 1G5 



house which contained a doe rabbit with a very young family, 

 I turned loose a ferret. The doe rabbit left her young ones, 

 and the latter, as soon as they smelled the ferret, began to 

 crawl about in so energetic a manner as to leave no doubt 

 that the cause of the commotion was fear, and not merely 

 the discomfort arising from the temporary absence of the 

 mother."* 



With reference to the instinctive endowments of this 

 kind in kittens, I may also quote the following, which I find 

 among Mr. Darwin's MSS : — 



" The many cases of inborn fear or ferocity in young 

 animals directed towards particular objects, as well as the 

 loss of these individualized passions, seems to me extremely 

 curious. Let any one who doubts their existence give a 

 mouse to a kitten taken early from its mother, and which has 

 never before seen one, and observe how soon the kitten 

 growls with hair erect, in a manner wholly different from 

 when at play or when fed with ordinary food. We cannot 

 suppose that the kitten has an inborn picture of a mouse 

 graven in its mind. But, as when an old hunter snorts with 

 eagerness at the very first sound of the horn, we must sup- 

 pose the old associations excite him almost as instantly as 

 when a sudden noise makes him start, so I imagine, with the 

 difference that the imagination has become hereditary instead 

 of being only fixed by habit, the kitten without any definite 

 anticipation trembles with excitement at the smell of the 

 mouse." 



The only other observations made by Mr. Spalding which 

 it is desirable to quote are those by which he proved experi- 

 mentally that young birds do not require, as was ordinarily 

 supposed, to be taught to fly, but fly instinctively. This fart 

 was proved by keeping young swallows caged until they were 

 Hedged, and then allowing them to escape. When we con- 

 sider the complicated muscular co-ordination required for flight, 

 the fact that young birds when fledged should be able to fly 

 at the first attempt constitutes another remarkable instance 

 of the perfection of instinct. Of course it is true that under 

 ordinary circumstances the parent birds encourage their 

 progeny to fly, but the experiments in question show that 

 such encouragement, or tuition, is not necessary to enable the 

 young birds to practise the ait. 



But it is among insects that we meet with the most re- 



• yaturc, vol. xi, p. 654. 



a 



