Deir | Correspondence. i ba BOE 
or continued after, the first union of the sexes, to accompany monogamous 
conjugal relations, and then, by a process of evolution, the steps in which 
may, I think, be partly traced and partly inferred, passed, as a culmination, 
into true Darwinian sexual selection. I do not however mean to imply 
that this has been the invariable course of development, or that mere 
promiscuity may not, at an earlier stage, have sometimes preceded mo- 
nogamy. 
At p. 151, speaking of the ‘‘ceremonies connected with coition,” Huxley 
says:— “The chief point to be remarked is that both cock and hen may 
adopt this attitude’’ — that is to say the prostrate attitude, preceding and 
accompanying coition, which rightly belongs to the female alone. My own 
_ observations, however, made in 1900 and 1901, were sufficient to assure me 
that this interchangeability of action as between the two sexes, in their 
sexual relations, extended to the actual pairing itself, and I have since con- 
firmed this in the case of the Little Grebe (or Dabchick), for, having closely 
and continuously watched a pair of these birds, established in a pond, and 
thus, as I may say, well under control, I have seen either bird alternately 
assume the part of either sex during coition. This reversal extended to the 
minutest particular, so that the false and true unions were indistinguish- 
able. Thus we have —for what else are we to term it? — functional 
hermaphrodism in both the Great Crested and Little Grebe. My observa- 
tions on the latter species were published in ‘Wild Life’ from July to 
December (inclusive), 1915. 
It is, I think, a legitimate inference that this dual functioning of either 
sex, in the primary and all-important sexual act, must (or is likely to) 
imply a similar duality of the sexual psychology, in each, and this would, 
in itself, account, or help in accounting for, the identity of much of the 
masculine and feminine conjugal display action in the Great Crested Grebe. 
I have made similar observations on the Moorhen — in which species also 
this identity exists — and, so far as the actual pairing is concerned, in the 
case of the Dovecote Pigeon. Also I have good first hand evidence of the 
same nature concerning the Mute Swan, and can myself speak as to very 
salient springtide antics carried out by both the male and female Whooper 
Swan, when conjugally united. To me it is almost inconceivable that these 
peculiar pairing habits have been brought about, independently, in differ- 
ent species, through the operation of more or less recent utilitarian causes. 
The root cause is, I believe, the joint inheritance, by all, and in each sex, 
through a common line of ancestry, dating from a remote past, of that 
sexual psychology which once co-existed with physiological hermaphrodism ; 
of which persistence, therefore, the lesser or secondary bisexual activities 
are also to be regarded as effects. It is, of course, obvious that, so far as 
the sexual mentality of birds is concerned, the above inference need not 
alone apply to species that have this odd habit of double coitional function- 
ing, for a general inherited tendency need not necessarily be accompanied 
by some particularly salient indication of it, in action. The study of man 
sufficiently illustrates this. 
