THE ADAPTATION OF ORGANISMS 73 



in a special pouch inside the mouth, a somewhat unique 

 position. 



Among birds, the evidence that can be brought for- 

 ward in support of the high standard of parental care 

 is so extensive that no one can doubt it. The care spent 

 on the building of the nest and on the feeding of the 

 young are such features of daily experience that they 

 are apt to be overlooked ; but who can ever forget, once 

 they have seen it, the care with which the bird teaches 

 its offspring to fly, to catch food, and to avoid danger, 

 and the eager willingness with which it is done ? 



Every phase of parental care among animals is but 

 another example of the struggle made by animals to 

 adapt themselves to their surroundings. 



We must always remember that the conditions of the 

 environment are infinitely varied throughout the world. 

 In no two regions are the conditions absolutely identical 

 for several consecutive seconds, and so the organism 

 must, as it were, keep pace with the ever-changing con- 

 ditions. In one region certain of the environmental 

 factors may be emphasised, in another, others ; and the 

 predominant factor generally induces a special type of 

 organism. 



