INFLUENCE OF THE PRIMARY REPRODUCTIVE 

 ORGANS ON THE SECONDARY SEXUAL 

 CHARACTERS. 



VERNON L. KELLOGG, 



Stanford Uni'uersity, California. 



This paper records the results of certain experiments on the 

 silkworm moth, Bottibyx ruori, testing {a) the possibility of the 

 regeneration of such important internal organs as the reproductive 

 glands, and (b) the influence on the secondary sexual characters 

 of the moth which the extirpation of the reproductive organs on 

 one or both sides in larvae of various ages might effect. 



The first question is a general one in regeneration, touching 

 particularly the relation of natural selection as a causative agent 

 to regeneration: external organs liable to natural mutilation 

 might be perhaps advantageously regenerative, but internal organs 

 not liable to mutilation could not, if regenerative, have this capa- 

 city of theirs explicable as a result of selection. The second 

 question concerns the immediate stimulus which l^ads to the 

 development in any individual of the secondary sexual characters 

 (ornamental tufts of hair, feathers or scales, defensive, offensive 

 or attractive processes, markings, etc., the peculiar clasping 

 organs, etc., composing the external genitalia). Certain biologists 

 hold that the stimulus for these secondary sexual characters in 

 any individual depends directly upon the presence of the primary 

 reproductive organs (ovaries or testes). 



J. W. Tutt^ discusses the latter question, quoting the ento- 

 mologist Wood, as follows: "The functions, then, of the repro- 

 ductive glands are twofold: on the one hand they supply germ 

 matter that resides within them with the means of developing and 



^Entomologists Record, 1900, Vol. XII, pp. 199-202. 



