Reflexes, Instincts, and Intelligence 641 



the female, but is immediately and strongly so after coming in contact with 

 her. Males with antennae on become strongly excited when a female is 

 brought within several inches of them. 



The protruded scent-glands of the female are withdrawn into the body 

 immediately on her being touched by a male. If the scent-glands are cut 

 off and put wholly apart from the female, males are as strongly attracted to 

 these isolated scent-glands as they are to unmutilated females; on the con- 

 trary they are not at all attracted to the mutilated females. If the cut-out 

 scent-glands are put by the side of and but a little apart from the female from 

 which they are taken, the males always neglect the near-by live female and 

 go directly to the scent-glands. Males attracted to the isolated scent-glands 

 remain by them persistently, moving excitedly around and around them and 

 over and over them with the external genitalia vainly trying to seize them. 



The behavior of males with the antenna of only one side removed is 

 striking. A male with left antenna off when within three or four inches of a 

 female (with protruded scent-glands) becomes strongly excited and moves 

 energetically around in repeated circles to the right, or rather in a flat spiral, 

 thus getting (usually) gradually nearer and nearer the female and finally 

 coming into contact with her. A male with right antenna off circles or 

 spirals to the left. It is a curious sight to see two males with right and left 

 antenna off, respectively, circling violently about in opposite directions when 

 the immobile female a few inches removed protrudes her scent-glands. 

 This behavior is quite in accordance with Loeb's explanation of the forward 

 movement of bilaterally symmetrical animals. 



The results of all the experiments tried show how rigorously the male 

 moths are controlled by the scent attraction (chemotropism) and how abso- 

 lutely dependent mating (the one adult performance of the males) is on this 

 reaction. If we can find specialized animals in a condition where response to 

 all attractions and repulsions (stimuli) but one are eliminated, we may readily 

 perceive the rigorous control exercised by this remaining one. We are, unfor- 

 tunately, in the general circumstances of animal life too much limited to the 

 use of very simply organized animals for reaction and reflex experimenta- 

 tion. This tends to make it difficult to carry over to the behavior of com- 

 plexly organized animals the physico-chemical interpretation which is 

 steadily gaining ground as the key to the understanding of the springs and 

 character of the behavior of the simplest organisms. But where the com- 

 plex stimuli and reactions that determine the behavior of complexly organized 

 forms can be isolated and studied, the inevitableness of much of this 

 behavior can be recognized. 



Instincts. Examples and accounts of instincts are scattered all through 

 this book. Complex and elaborate behavior in connection with egg-laying, 

 care of young, food-getting, defense, offense, nest-making, parasitic, com- 



