FLIGHT-FUNCTION IN THE SILKWORM. I 23 



Thus it was ascertained that many male moths were not 

 powerless with respect to flight. The moth has not " forgotten " 

 how to fly. It would appear, however, that, during the first 

 few days of the life of the moth the flight reflexes are under 

 inhibition and remain so during the exercise of the mating 

 reflexes. Restrained from mating, however, as has been demon- 

 strated, the flight instinct asserts itself, and the flight reflexes are 

 "let loose" as it were. Neither natural selection, which by 

 carrying a "flier " far from a mate, and thus leaving it without 

 offspring, nor the discontinuance of the need for flight have 

 served to eradicate the possibility of exercising the flight function. 



As stated, the moths thus far experimented with were deprived 

 of mates. Later, a large series of moths was isolated after 

 mating had taken place. They were first allowed to mate 

 normally. When they had voluntarily left the female they were 

 isolated as before. The result was the same. When first 

 isolated they were quiet. After several days had elapsed a large 

 percentage entered into the "fluttering" condition and flight 

 ensued. 



During the very beginning of the " fluttering " condition if a 

 female is brought near, the male is attracted to her and mating 

 takes place. If, however, the fluttering condition is well under 

 way the male pays no attention to the female but flutters past 

 her or over her, it may be, and finally takes to wing. 



It would seem, therefore, from the foregoing observations that 

 the flight reflex is, at the time the insect leaves its cocoon, part 

 of the moth's sum-total of inheritance but is merely under 

 inhibition. 



The mating instinct is, however, exercisable at once, that is, 

 is immediately dominant. A sufficiently long inhibition of the 

 mating instinct appears, in a large number of individuals, to aug- 

 ment the flight reflex. Furthermore, with the flight reflex 

 released, the mating reflexes are, for the time being, inhibited, or 

 at least manifestation of the flight reflex takes place only during 

 suspension of the activities of the mating instinct, and during the 

 manifestation of the mating activity, cannot be aroused. 



This manifestation is wholly, however, without purpose, is 

 purely non-adapted. . It is a manifestation apparently of what 



