1900.] 103 



quite different, and may be said almost to take a new departure, but 

 no corresponding variation takes place in the female, which conforms 

 accurately to the fine-ended or suhjectana type. This unexpected 

 independence is not, I believe, confined to a genus here and there, but 

 will be found the almost universal rule, that is to say, each set of 

 organs varies, up to a certain point, irrespectively of the other. 

 Hence the conclusion is inevitable that much of the variation that we 

 find in the male appendages is of a neutral character, neither useful 

 nor hurtful to them as clasping organs. 



There is, however, another aspect of the subject : all this amazing 

 fertility of shape is dependent in some way upon the presence of the 

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

 they be removed at a sufiiciently early date in the life of the larva, 

 the transformation of the last larval segment into the armature of the 

 imago would not occur, much as the emasculation of the deer prevents 

 the development of its horns. Now, accepting Weismann's division 

 of the individual into the soma and germ-plasm, it seems to me that 

 if we are to conceive an organic whole, some connecting link is re- 

 quired to bring the two into mutual relationship. Such a link the 

 reproductive glands, whether testes or ovaries, can supply. To hold 

 that the production of the spermatozoa or the ova, as the case may 

 be, is the sum and substance of the office of these glands, is to shut 

 our eyes to the immense control they exercise over the development 

 of the soma. Moreover, there is very good reason to believe that 

 these structural functions, as we may perhaps for convenience call 

 them, are quite distinct from their reproductive functions, and even 

 independent of them. The two sets are seldom in full activity at the 

 same time, the former for the most part antedating the latter, and 

 often to a considerable extent. Again, the organs may be capable of 

 discharging one set of functions, and incapable as regards the other. 

 In such cases the failure is usually on the side of the reproductive 

 functions. Examples of undescended testis are familiar enough to 

 the surgeon and the physiologist, in this predicament the organs are 

 small and starved, and utterly incapable of producing spermatozoa, 

 yet all the virile characters of the individual may be present, and that 

 to a full degree of perfection, fertility alone excepted. 



The functions then of the reproductive glands are twofold : on 

 the one hand they supply the 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 secondary sexual characters. 



