426 



GENERAL PRINCIPLES 



female disintegrates normally in order to free the contained 

 embryos. 



859. Though such cases are rather numerous they must 

 still be regarded as exceptional. Usually the best interests 

 of the species are served by that which favors the individual. 

 We will, therefore, inquire into that class of adaptation by 

 which the individual profits more directly. Much of the 

 struggle for existence is in reality a struggle between indi- 

 viduals; it may be individuals of the same or of different 



Fig. 263. — A Juncus swamp in which is found a large gray and olive-brown 

 striped grasshopper. The color of the grasshopper is protective in such an 

 environment. Coast of__North CaroHna. 



species. Illustrations of thi? principle are usually taken 

 chiefly from animals, but one from the vegetable kingdom 

 may also be introduced here. The difficult conditions under 

 which desert plants grow makes the number of individual 

 plants which succeed relatively small. Therefore, the life 

 of an individual plant is of more value to the species. It is, 

 therefore, not strange that such plants are wondei fully well 

 protected. The spines of the cacti render them practically 

 immune to the attacks of animals. To a less degree spines 



