396 TRANSMISSION 



possible. In a box they will crawl along the bottom till they 

 come to a side. Here they can touch two surfaces, and motion 

 will then be along the groove where the side meets the bottom 

 until they reach the corner, where a third surface joins, when 

 they are likely not to turn the corner (unless impelled by some 

 stronger instinct) but to come to rest in contact with three 

 surfaces, this affording, apparently, the highest attainable satis- 

 faction. If a tubular opening be found, insects of this instinct 

 will crowd into it, if possible, or at least make the attempt. 1 

 This instinct to seek greater comfort by getting snugly placed 

 in contact with foreign bodies is present in the higher animals 

 and in man, and it accounts for many of the movements and 

 resting positions so commonly seen. 



That this action is not the result of a purpose to hide is 

 evidenced by the fact that neither light nor darkness has any 

 effect upon it, and that the instinct is not changed even by the 

 removal of the brain. In nature, of course, places that will satisfy 

 this instinct are generally shut away from light, and insects so 

 bestowed are also hidden, a fact that has given rise to the 

 tradition that the purpose was to secrete themselves from pred- 

 atory enemies. Of course the tradition itself is not consistent, 

 for intelligent animals seeking food soon learn the favorite haunts 

 of their prey. They therefore know precisely where to look for 

 them and speedily turn them out. 



We have already seen that protoplasm may be excited to 

 action by a great variety of external agents (light, heat, elec- 

 tricity, chemical substances) ; that the character of protoplasmic 

 activity may be modified by certain of these external forces, 

 notably light and chemical attraction ; that the direction of 

 movement or of growth may also be influenced by the same 

 class of agents (light, chemical substances, heat, gravity) ; and 

 that in all these ways the activities of living beings are largely 

 dependent upon the nature of the outside forces with which they 

 come into contact. Here lies, to a very large extent, the initial 

 cause of those external acts we ordinarily speak of as instincts, 

 and the remaining elements of causation are to be sought in the 

 internal mechanism of the creature. In all likelihood it is not 



1 Loeb, Physiology of the Brain, p. 93. 



