525 
On 
COURTSHIP OF THE GREAT CRESTED GREBE, 
be performed by the two birds together, there is nothing to 
account for them as they now stand but some such process as I 
have just sketched under the name of Mutual Selection 
Then there comes the question of the facultative reversal of the 
act of pairing (or, possibly, only of preliminary pairing-attitudes). 
The other cases noted by Selous (Pigeon and Moorhen) differ in 
that the male crouched to the female directly after the act 
of pairing, who at once proceeded to play the male’s part. In 
the Grebe there was always a long interval before the ‘“ reversal 
of instinct ” took place. 
In all, however, it is very difficult to see how to account for it, 
except on the assumption that there has been a reciprocal 
“transference” of pairing-instincts. This transference may be 
apparent or real. It is apparent if we believe that the units for 
such sexual characters are equally present in the germ-plasm of 
both sexes, and that the chavacters themselves do not appear in 
the other sex (or only appear as rudiments) asa result of the 
great primary sex-difference. 
If the transference is real, then one must assume that the 
zygotic constitution of the two sexes is different in regard to 
secondary as well as primary differences, but that there is a 
constant tendency—depending on some as yet unknown process— 
to transfer such characters to the opposite sex. (Hybridization 
experiments, where the female of a species can transmit to her 
male hybrid offspring the secondary sexual characters of her own 
species, indicate that the first method isthe true one.) How else 
than in one of these two ways can we explain transference in 
both directions? This is seen, for example, in man, where a male 
organ, the moustache, appears rudimentarily in the female, and 
female organs, the mamme, appear rudimentarily in the male: 
in abnormal cases, besides, the transference may be complete, the 
organs being completely developed in the wrong sex. Such 
moustached women and men with breasts again support the idea 
that the transference is not a real transference, but consists in 
the removal of an inhibition only. 
(L would not trouble to mention the theory that these appear- 
ances of characters of one sex in the other are due to descent 
from a hermaphrodite ancestor, were it not actually the case 
that Metchnikoff has advanced it. It is enough to point out that 
if this were so, the primitive mammal must have been a herma- 
phro lite.) 
To us it makes little odds whether there is inhibition alone or 
transference followed by inhibition. In both cases the character 
will be in antagonism with the inhibitor: supposing that there 
is no longer any need to inhibit a character of one sex in the 
other, then on Darwinian and Weismannian principles the in- 
hibiting “force” will atrophy, and the character, remaining 
as strong as ever, will appear equally in both sexes. 
Apply this to the present case. Birds are for the most part 
Bi 
