MYSTERIES OF LIFE AND MIND 



towards the light. To the birds we ascribe intelli- 

 gence, to the flower no more than the attraction of 

 light. Yet it seems as if the self -same forces rule 

 over both. 



This is what Dr. Loeb set himself to prove. And 

 with it, to explain the origin of all the so-called in- 

 stincts. When the new-born caterpillar climbs to 

 the end of a branch where it may find the fresh 

 bud on which it feeds, it seems as if some dim intelli- 

 gence were at work. When it is satiated, it climbs 

 down again. A fly will lay its eggs in meat, where- 

 on its larvae may feed, but not on fat. These and 

 a thousand other marvels of a seeming shaping 

 towards an end have filled physiology with a meta- 

 physical fog. 



In a series of interesting researches, Dr. Loeb 

 showed how all these wonderful adaptations to an 

 end could be explained in a very simple way. Young 

 caterpillars, for example, will follow the light, so 

 long as they are hungry. If they find no food they 

 will keep climbing, conceivably until they die. 

 When they are cold, they will not move. When 

 the warm sun comes in the spring, they begin to 

 crawl upward. They will do this anywhere and 

 on any substance. When they come in contact 

 with food, they begin to eat. When they are fed, 

 they will crawl away from the light. All that is 

 needful to assume is that in the hungry condition 



2OT 



