406 Evolution and Adaptation 



The protection of the young by their parents from the 

 attacks of other animals appears to be a somewhat com- 

 plex instinct, and it is interesting to note that the protection 

 is extended to the young only so long as they are in need 

 of it, and as soon as they are able to shift for themselves 

 the maternal protection is withdrawn. 



The instinct of the young chick to seize in its beak any 

 small moving object is a simple and useful reflex action, but if 

 the object should happen to be a bee which stings the chick, 

 another bee or similar insect will not be seized. Here we see 

 that a reflex has been changed, and changed with amazing 

 quickness. Moreover, the chick has learnt to associate this 

 experience with a particular sort of moving object. It is this 

 power to benefit by the result of a brief experience that is one 

 of the most advantageous properties of the organism. 



Young chicks first show a drinking reflex if by chance 

 their beaks are wet by water. At once the head is lifted 

 up, and the drop of water passes down the throat. In this 

 way the chick first learns the meaning of water, and no doubt 

 soon comes to associate it with its own condition of thirst. 

 The sight of water produces no effect on the inexperienced 

 chick, and it may even stand with its feet in the water with- 

 out drinking ; but as soon as it touches, by chance, the water 

 with its beak, the reflex, or rather the set of reflexes is 

 started. 



A more complicated instinct is that shown by the spider 

 in making its web. In some cases the young are born from 

 eggs laid in the preceding summer, and can have had, there- 

 fore, no experience of what a web is like ; and yet, when they 

 come to build this wonderfully complex structure, they do so 

 in a manner that is strictly characteristic of the species. 



The formation of the comb by bees, in which process, 

 with a minimum of wax, they secure a maximum number of 

 small storehouses in which to keep their honey and rear their 

 young, is often cited as a remarkable case of adaptation. 



