Secondary Sexual Characters 441 
Mayer also made some experiments to test whether the females 
show a choice in selecting the males. The male is dark or black- 
ish; the female reddish brown. The wings of a female were cut 
off and glued on to the wings of a male, so that he appeared like 
a female; nevertheless he was accepted by a female, no aversion 
was manifested, and the mating was normal. The converse 
experiment was also made. The wings of a female were cut off 
near the base and the wings of a male were glued on in their 
place. Such females looked like males, yet the males mated 
with them as with normal individuals. Clearly, then, neither the 
coloration of the male nor of the female can be supposed to 
have a selective value. 
Males pay no attention to males with female wings; but will 
pair readily with a female both of whose wings have been cut off. 
Even when the wings of both the male and the female have 
been removed, pairing occurs if they are brought together. 
One series of experiments of this kind is not perhaps conclu- 
sive, and there is great need for more experimental work along 
these lines. 
There are many other serious objections to be urged against 
Darwin’s theory. I shall give here only a few of the more 
important ones." 
In most groups of unisexual animals — and it is only such 
that come under the theory — the number of males and fe- 
males is approximately equal. Therefore even if we admit 
that the most ornamented individuals are first selected, the 
remainder of the females must pair with the less ornamented 
males. In consequence nothing would be gained in successive 
generations. 
It is assumed that by the selection of individual or fluctuating 
differences the character of the males can be greatly changed. 
It may be questioned if this is possible, even if rigorous selection 
be admitted to occur. It is doubtful if anything more could be 
accomplished in this way than to maintain the standard at a 
1In my book on “Evolution and Adaptation” I have discussed this topic 
more fully. 
