Introductory ij 



And who were the gardeners whose absence proved to 

 be of such vital importance? Humble bees, only humble 

 bees! and indeed, only the particular species of humble 

 bees which wait upon scarlet-runners. There were plenty 

 of others, but they did not understand, though very prob- 

 ably they would have come to do so in the course of a few 

 seasons. As it w^as, however, failing these insect labor- 

 ers, there was nothing to be done — nothing to take their 

 place. Man has not yet discovered any substitute for the 

 bee. 



In the following chapters we shall consider in more 

 detail the various ways and means by which the work of 

 the great farm is carried on by the natural laborers, and 

 also some of the changes made in it by the work and 

 unconscious influence of man. 



QUESTIONS FOR REVIEW 



1. How have our ideas of the fertility of the earth been 

 changed in recent years? 



2. What proportion of the earth in Europe has been brought 

 under cultivation? 



3. How do the animals and vegetables used by man com- 

 pare in number with nature's supply? 



4. Show how nature makes use of every possible oppor- 

 tunity for raising crops. 



5. How do man and his animals sometimes help to increase 

 the desert regions? 



6. Show how the farmer is dependent at every step upon 

 nature's laborers. 



