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264 THE FEELINGS AND EMOTIONS 
accepts that mate which by his song or otherwise excites in 
sufficient degree the pairing impulse ; if others fail to excite 
this impulse, they are not accepted. Even Mr. A. R. Wallace, 
who rejects the theory save in a very subordinate form, says * 
that “it may be admitted, as highly probable, that the female 
is pleased or excited by the display,” and speaks f of a possibl> 
choice of “ the most vigorous, defiant, and mettlesome male,” 
giving, moreover,{ several telling examples of preferential 
mating. Stripped of all its unnecessary esthetic surplusage, 
at any rate so far as this implies an esthetic ideal, or esthetic 
motive, the hypothesis of sexual selection suggests that the 
accepted mate is the one which adequately evokes the pairing 
impulse. 
Here Dr. Groos makes an interesting and important con- 
tribution to the subject. He lays stress on the coyness and 
reluctance of the female, and illustrates it by examples derived 
from observation. ‘Thus the female cuckoo answers the call 
of her mate with an alluring laugh that excites him to the 
utmost, but it is long before she gives herself up to him. 
A mad chase through tree-tops ensues, during which she con- 
stantly incites him with that mocking call, till the poor fellow 
is fairly driven crazy. The female kingfisher often torments 
her devoted lover for half a day, coming and calling him, and 
then taking to flight. But she never lets him out of her sight 
the while, looking back as she flies and measuring her speed, 
and wheeling back when he suddenly gives up the pursuit. 
The bower-bird leads her mate a chase up and down their 
skilfully built pleasure-house, and many other birds behave in 
a similar way. The male must exercise all his arts before her 
reluctance is overcome. She leads him on from limb to limb, 
from tree to tree, until it seems that the tantalizing change 
from allurement to resistance must include an element of 
mischievous playfulness.” § 
Professor Groos regards the instinctive coyness of the 
female as the most efficient means of preventing the too early 
* “Darwinism,” p. 285. + Op. cit., p. 293. 
$ Op. cit., p. 172. § Op. cit., pp. 285, 286. 
