304 AN INTRODUCTION TO ZOOLOGY 



selves. The division of labor among the workers is due to in- 

 stinct; although each individual is equipped with the many 

 structural features that so wonderfully adapt it to its mode of 

 life, only one sort of work is undertaken at a time, and this in all 

 cases is the thing most needed by the hive. For example, as 

 soon as a hollow tree is selected and cleaned, the workers proceed 

 to secrete wax and build comb; when eggs are laid, pollen is 

 gathered and stored with which to feed the forthcoming h 

 during the pollen and nectar gathering season, each worker 

 lects either the one or the other, and the pollen gathered on or 

 trip is all of one color, having been collected evidently from 01 

 kind of flower. Altruistic instincts such as these are especiall; 

 abundant in social animals, and among these may be classed 

 social instinct itself. On the other hand, the instincts of feeding 

 of self-defense, of battling for the supremacy of the hive, and 

 playing before the hive on bright days, may be said to be egoistic 

 These definitions and examples of instinctive acts are nc 

 accepted by all scientists; and of recent years there has been 

 tendency to consider them as tropic responses to stimuli. Thi 

 one authority attributes all the activities of ants and bees 

 reflex responses to chemical and other stimuli (229). The ei 

 nent physiologist Loeb says: " My investigations on the helk 

 tropism of animals led me to analyze in a few cases the conditioi 

 which determine the apparently accidental direction of aninu 

 movements which, according to traditional notions, are call* 

 voluntary or instinctive. Wherever I have thus far investigate 

 the cause of such ' voluntary ' or ' instinctive ' movements 

 animals, I have without exception discovered such circumstances 

 at work as are known in inanimate nature as determinate move- 

 ments. By the help of these causes it is possible to control the 

 ' voluntary ' movements of a living animal just as securely and 

 unequivocally as the engineer has been able to control the move- 

 ments in inanimate nature. What has been taken for the effect 

 of ' will ' or ' instinct ' is in reality the effect of light, of gravity, 

 of friction, of chemical forces, etc." (252, p. 107). According 





