Dr. E. A. Cockayne on the relation between Gonads. 337 



The short account of the action of the ductless glands 

 given above is that most commonly accepted as correct, 

 but it must be mentioned that Blair Bell and others 

 consider that they all have an equally powerful influence 

 on the development of the secondary sexual characters, 

 and that, although alike in appearance in the two sexes, 

 the pituitary, suprarenal, and other glands of the male and 

 female, produce internal secretions as unlike as those of 

 the ovary and testis themselves. 



It is important to examine what evidence there is for 

 and against the existence of a similar control in insects. 

 The best evidence is afforded by — 



(1) Experimental castration and transplantation of the 

 gonads in Lepidoptera. 



(2) Temperature experiments in Lepidoptera. 



(3) Stylopisation in Hymenoptera. 



(4) Gynandromorphs and Intersexes. 



Castration experiments have been performed by Oude- 

 mans, Kellogg and Meisenheimer. 



Oudemans removed the testes or ovaries from larvae of 

 Lymantria dispar before the penultimate and last moults ; 

 thirty out of sixty survived. Castrated males copulated 

 and castrated females tried to lay, but merely deposited 

 the tuft of wool with which the normal females cover 

 their eggs; their external appearance was unaffected. 



Kellogg experimented on silkworms, Bombyx mori, and 

 in no case was any change in the secondary sexual characters 

 produced. 



Meisenheimer castrated 600 larvae of Lymantria dispar 

 and bred 186 imagines. Those operated on before the 

 second moult always died, but some survived which were 

 operated on between the second and third, and third and 

 fourth moults. None of the imagines were altered in 

 appearance. 



Transplantation of the ovaries or testes into larvae of 

 which the testes or ovaries had been removed also failed 

 to alter their secondary sexual characters; nor was any 

 effect produced by forming artificial hermaphrodites, 

 though the transplanted gonads grew. 



These experiments are against the existence of a rela- 

 tionship between the gonads and secondary sexual charac- 

 ters such as is found in vertebrates. 



By means of heat or cold acting for varying periods on 

 the pupae of certain Lepidoptera the females can be made 



