COURTSHIP OF THE GREAT CRESTED GREBE. 507 
an incentive to the active bird, as a sign of readiness to pair. 
The active bird may or may not respond. 
(3) As a symbol, the attitude is obviously more important than 
the actual ascent on to the nest, since the attitude is used only in 
pairing, while the birds may ascend the nest for various purposes; 
and, in addition, the assumption of the attitude comes after the 
ascent, and is thus in time more immediately associated with 
the act of pairing. Thus the attitude by itself comes to be used 
on the open water (though always close to the nest) as a sign of 
readiness to pair. We may say that readiness to pair is indicated 
precociously —it is pushed back astep. Such processes of pushing 
back are very common in early ontogeny ; embryologists then say 
that the time of appearance of the character is cenogenetic (even 
though the character itself, as here, may be palingenetic). The 
phylogenetic change has here been precisely similar ; the only 
difference is that the displacement affects a mature instead of a 
very early period of lite. 
(4) The attitude being now sometimes a mere symbol can be, 
and is, employed by either the active or the passive bird. In 
fact, when one bird employs it thus symbolically, the other 
usually responds by immediately repeating this symbolic use. 
(5) From useful symbolism to mere ritual is the last step—one 
that has taken place often enough in various human affairs. It 
appears that these actions and attitudes, once symbolic of certain 
states of mind and leading up to certain definite ends, lose their 
active symbolism and become ends in themselves. When I say 
that they lose their active symbolism, I mean that they are now 
not so much associated with readiness to pair as with the vague 
idea of pairing in general. Thus associated with pleasurable and 
exciting emotions, they may become the channels through which 
these emotions can express themselves, and so change from 
purposeful stimuli to further action into merely pleasurable self- 
exhausting processes (see below). It is at least hard to see how 
to explain such happenings as that described on p. 534, (c) 6, 
where first one bird and then the other goes into the passive 
position on the open water, after which there is simply a 
resumption of feeding or preening. 
Another general point worth noticing is this:—-In the case of 
this Grebe the male has even less possibility of enforcing his 
desires than the majority of birds. In a few birds the male is 
not so helpless. The ordinary Barndoor Cock, for instance, is 
often rather forcible in his methods. In the Wild Duck (Anas 
boschas L.) the drakes often kill the ducks by continued tread- 
ing*. Somewhat similar forcible pairing is recorded of the 
Mute Swan (Cygnus olor). In such species it is by no means 
necessary for the race that the act of pairing should be par- 
ticularly pleasant to the female. In most birds, however, the 
female has the upper hand: she can always prevent the cock 
* Huxley, Biol. Centralbl. 1912. 
Proc. Zoot. Soc.—1914, No. XXXVI. 36 
