PEIMARY AND SECONDARY SEXUAL CHARACTERS IN LEPIDOPTERA. 199 



The connection between Primary and Secondary Sexual Characters 



in Lepidoptera. 



By J. W. TUTT, F.E.S. 



Not the least iuterestiug of the various pohits discusse'I iii Df. 

 "Wood's recent paper on certain Lithocolletids (Ent. JIo. Ma(f.) is the 

 final chapter on the biological aspects of the male genitalia. The 

 working theory advanced is certainly far-reaching in its application, 

 and one suspects that some first class entomologist will ere long pat it 

 to the test of practical application. 



One is, indeed, astonished that there should he the remarkable 

 variety which Dr. Wood shows to exist in the structure of these 

 organs among such small insects, and that closely allied species 

 should present such wide differences is also suffisiently striking, and 

 one is inclined to agree with the author that this variation is not 

 solely to prevent unnatural unions. It is not, however, this i^articular 

 view of the subject to which we wish to refer, but rather to a side 

 issue growing out of one of the points raised by Dr. AYood. 



Dr. Wood concludes that " much of the variation that we find in 

 the male appendages is of a neutral character, neither useful nor hurt- 

 ful to them as clasping organs." . . . and that '' all this amazing 

 fertility of sliape is dependent in some way upon tlie presence of the 

 reproductive glands or testes, for it can scarcely be doubted that could 

 they be removed at a sufficiently early date in the life of the lai'\a, 

 the transformation of the last larval segment into tlic armatui-c oi' tlir 

 imago would not occur, much as the euiasculatiou of the deei- prevoiUs 

 the development of its horns," He then goes on to suggest that the 

 ofdce of the reproductive glands (testes or ovaries) is twofold ; (1) The 

 production of spermatozoa or ova. (2) The control of the development 

 of the soma. These two functions are rarely in full activity at the 

 same time .... and the organs may be capable of discharging 

 one set of functions and incapable as regards the other. He says : 

 " The functions then of the reproductive glands are tAvofold ; on the 

 one hand they supply germ-matter that resides within them with the 

 means of developing and multiplying ; and, on the other hand, they 

 modify and even originate those parts of the soma which are lumped 

 together under the name of the secondary sexual characters. Now, 

 the more minutely Ave investigate and classify our insects the more 

 commonly do we come upon instances in which tlie only coarse and 

 tangible characters by Avhich one species may be distinguished with 

 certainty from another closely allied to ih-; lie in these secondary sexual 

 structures ; in fact the structures constitute for us the specific 

 characters. Hence the conclusion seems inevitable, that many of the 

 characters that go to form a species have their start in some primary 

 change in the reproductive glands and that these organs are not 

 merely passive agents concerned in the nourishment of the germ-matter, 

 but do themselves take an active and creative part in the genesis of 

 species." 



Since I have been studying the Lachneids (Lasiocampids) 1 have 

 been brought face to face Avith the necessity of forming some sort of 

 opinion as to the cause of the external peculiarities of gynandrc- 

 morphism, and some time since I came to the conclusions that Dr. 

 Wood Jvas so ;il")h- formulated. I have alreadA- stated., in the second 



