48 THE HUMANIZING OF THE BRUTE. 



they find the desired food. That they did not do so 

 in case of L,oeb's test-tubes is merely due to the fact 

 that they were not aware of the food, since this was 

 at an altogether unusual and dark place. Hunger, 

 and nothing else than hunger, is the cause which im- 

 pels the animal to follow the guidance of its senses in 

 order to appease that craving. This is the sole rea- 

 son why, as soon as the caterpillars have eaten, and 

 at the time of moulting, "it is almost impossible to 

 show any effect of light or gravity upon them. ' ' It 

 is not heliotropism, but hungertropism, or, to speak 

 still more scientifically limotropism, that accounts for 

 the caterpillars creeping upward. 



Prof. I,oeb takes the liberty of sneering at the use of 

 words like "instinct" to designate causes of move- 

 ment, and says that such causes stand upon the same 

 plane "as the supernatural powers of theologians, 

 which are also said to determine motions, but upon 

 which an engineer could not well rely. " He more- 

 over declares the method of Scholastic thinking a 

 "handicap" which, by phrases like "instinct" serves 

 to ignore or conceal the true problem involved. 



Prof. Loeb forgets that there are two kinds of prob- 

 lems to be solved: the one referring to the more re- 

 mote and ultimate causes of phenomena; the other 

 pertaining to their proximate causes and relations. 

 Both are objects worthy of the intellect of man, and 

 neither is opposed to the other. But while the second 

 is of interest to the specialist only, and has no bearing 

 on the great questions of human life, the other is of 

 interest to every man who is anxious to study the 

 foundations upon which his relations to his fellow- 



