230 APPLIED BIOLOGY 



less cases there are reasons for believing that under different 

 conditions of past times some things not now useful may 

 have had a use. 



The tendency to look for usefulness in everything is 

 strong in the human mind. Long ago all nature was looked 

 upon as made for the use of man ; plants for man to eat and 

 use in other ways, and animals for human food, clothing, 

 beasts of burden, pets, etc. And, after all, it is not very sur- 

 prising that men got into this way of thinking, for so many 

 animals and plants are useful to us. This fact is impressed 

 upon the reader of such books as Shaler's " Domesticated 

 Animals,' 7 Wood's " Dominion of Man," and books dealing 

 with useful plants. But within the past fifty years this 

 attitude has changed, and now scientific men do not look 

 upon all nature as having been made for the direct use of 

 man, but believe that animals and plants have a reason for 

 existence even if there were no human beings in the world. 

 In fact, geology has shown that vast numbers of organisms 

 lived on this earth millions of years before man appeared. 



The passing of the view that all the world is arranged with 

 direct reference to use by man has been followed by the tend- 

 ency to look upon all things in each animal and plant as 

 useful to itself, to its offspring, or to its kind or species. This 

 also was the outcome of the truth that a large number of 

 things are obviously useful. There can be no doubt concern- 

 ing the usefulness of some adaptations of flowers to insects, 

 of plants to storage of food, of leaves in the light-relation, 

 and of some seeds for distribution ; but no one knows a use 

 for many other things (e.g., prickles, thorns, hairs, and the 

 brilliant colors in many plants, or the fleshy parts of some 

 inedible fruits). Hence science does not warrant the con- 

 clusion that, even if many things are not arranged for 

 the use of man, they are all of use to the organisms which 

 possess them. The important point in the whole matter is 

 the fact that many, very many, modified structures are 



