BRITISH WARBLERS 
required, as a study of the life of the two Whitethroats will 
reveal; for the male Lesser Whitethroat spreads out its 
wings and tail in presence of the female in the same way 
as the female when anxious about her progeny, and the 
behaviour of the female Whitethroat, when her nest is 
intruded upon, is identical with her behaviour sometimes when 
in the presence of the male. And it can by no means be 
said that, in either of these two cases, there is any difference, 
so far as the attitudes assumed are concerned, at one moment 
from that at another; in this respect only is any difference 
observable, that whereas at the period of sexual activity the 
flapping of the wings takes place while the bird is in the 
bushes, but not actually on, although frequently close to, 
the ground, at the period of parental care it occurs for the 
most part when the bird is actually on the ground. But 
assuredly the difference between a spreading and waving of 
the wings upon the ground, and a similar spreading and 
waving a few feet above it, can never be pointed to as one 
of sufficient importance to form the basis of an entirely novel 
explanation. These facts, taken from the lives of two species 
only, are clearly insufficient, where so large a number of 
species are involved, until supplemented by others of a 
similar nature; and although I attach considerable signifi- 
cance to them, yet it is not on them alone that my conclu- 
sions are based. Rather do I look to the absence of evidence 
in support of the simulation theory on the one hand, and 
the functional similarity on the other, as furnishing the more 
important considerations. or since the activities, occurring 
at different periods of excitement, resemble one another to 
so large an extent throughout bird life in general, it is 
probable @ priort that they have but one common origin. 
Therefore, until considerations of an a posterior’ kind are 
supplied, tending to show that there is some difference in kind 
between those which occur during the period in which the 
parental instinct is uppermost, and those which occur at 
other periods, making it virtually impossible that they can 
14 
