INSECT NESTS SJOSTEDT. 347 



bearing a larva between its mandibles. The larva is held by the 

 body, with the head upward. Thus their own larvae serve to make a 

 silken net to join the leaves. Due to the pressure of the mandibles, 

 doubtless, the larva excretes from its mouth a liquid which in solidi- 

 fying forms a silk thread, and by carrying the head of the larva 

 from the edge of one leaf to the edge of the other the ant obtains a 

 web which assures the adherence of the two leaves. In the same 

 way the interior walls of the nest are formed, the larva thus function- 

 ing as spinning wheel and as bobbin. An anatomical examination of 

 these larvae shows that the setiferous glands in them attain dimen- 

 sions not found in any other of the Hymenoptera. 



VI. 



From a scientific point of view, in the light of these complex mani- 

 festations, the question arises as to whether or not they are expres- 

 sions of intelligence — whether the insects at work are conscious of 

 the procedure and of the importance of the end to be attained, or 

 whether their actions are merely the result of instinct, the insects 

 being incapable of reasoning. 



If the animals were simply mechanisms with no spontaneity, a 

 strict identity ought to be observed in their methods of work and 

 construction. But with certain species at least a remarkable adapta- 

 bility to variations in the surrounding conditions is shown, these 

 adaptations being transformed, if the causes persist, into hereditary 

 characters. 



Forel, the eminent myrmecologist and psychologist, thus sums up 

 the observations made during more than 20 years on the psychology 

 of insects : 



All the characteristics of man might be derived from the characteristics of 

 the higher animals, and all the characteristics of the higher animals might be 

 derived from those of the lower animals. In other words, the evolutionary 

 formula applies equally in the realm of psychology as in the physiological 

 domain. 



