INTRODUCTION, xxiii 



There is yet another phrase in the work of Geddes and Thomson 

 which is best discussed as a whole than in parts. It is as 

 follows : " Brilliancy of colour, exuberance of hair and feathers, 

 activity of scent glands, and even the development of weapons are not 

 and cannot be (except teleologically) explained by " sexual selection," 

 but in origin and continued development are outcrops of a male as 

 opposed to a female constitution. To sum up in a paradox, all second- 

 ary sexual characters are at bottom primary and are expressions of 

 the same general habits of body (or to use the medical term diathesis}, 

 as that which results in the production of male elements in the one 

 case or female elements in the other." I quite agree with these authors 

 that these secondary characters cannot be explained by the direct 

 action of " sexual selection," but is it sufficient to say that they are 

 simply the results of a male as opposed to a female constitution. In 

 lepidoptera at any rate there appears to be some very good ground for 

 supposing that these are transmitted from generation to generation, 

 sometimes more perfectly developed than others, but still certainly 

 transmitted. It is not so evident that secondary sexual characters are at 

 bottom primary, except in the general way that they always accompany 

 the primary sexual characters, a fact that makes them secondary charac- 

 ters, neither is it so clear that because an organism has in it the special 

 requirements to develop a particular sex, which will be accompanied 

 by other characters, that these latter are produced in the same way and on 

 the same basis, although the two happen to be coincident in the same 

 organism, for if we look on these ornaments from Wallace's standpoint 

 as the " natural product and direct outcome of superabundant health 

 and vigour," it is quite possible to assume and imagine a condition 

 sufficiently differentiated to produce primary sexual characters without 

 the superabundant energy necessary to produce the secondary cha- 

 racters. I really am not quite clear that in insects they are ex- 

 pressions of the same general habit of body, although I quite recognise 

 the intimate connection between the two, but at the same time, of one 

 thing I feel certain, that they are only the indirect outcome of male- 

 ness, inasmuch as only the male normally, in lepidoptera at least, has 

 sufficient surplus energy to develop such secondary characters, the great 

 mass of energy in the female necessary for the perfection of the ovaries 

 and ova reducing the quantity left for such characters to a minimum. 

 In cases where the females are in a transition state, as in some Lyccence 

 (females developing blue scales, &c.), the females, although frequently 

 possessing some of the male colour, are as frequently without it, the 

 result probably being more or less directly dependent on nutrition. 



(11). SECONDARY CHARACTERS CONNECTED WITH OVIPOSITION. 

 These organs are so closely connected with the primary sexual 

 characters that they should properly be omitted, but the interest 

 attaching to them is so great, that this must be my excuse for briefly 

 referring to them. They were recently discovered by Drs. Chapman 

 and Wood, and consist of an apparatus, by means of which the females 

 of certain moths cut out a pocket in a leaf and lay their eggs in the 

 pocket within the substance of the leaf, or, otherwise, puncture a hole 

 in a stem &c., in which to lay the egg. This apparatus was detected 

 simultaneously by these two observant entomologists Dr. Wood 

 having made his observations on Micropteryx semipurpurella. Dr. 



