440 Experimental Zoology 



was first developed in the male and was then transferred to 

 the individuals of the other sex. 



There are serious objections to the theory of sexual selection, 

 some of which Darwin himself has considered. He points 

 out, for instance, that his theory demands "powers of dis- 

 crimination and taste on the part of the females which will 

 at first appear extremely improbable." The few instances that 

 Darwin gives to show that such discrimination may really exist 

 are far from convincing. Amongst domesticated animals there 

 is very little evidence that can be brought forward to support this 

 view, and much that is opposed to it. It must be borne in mind 

 that even although the female may be excited by the presence of 

 the male or by his antics and demonstrations, it is essential 

 that she consistently select the most adorned in order that any 

 result may follow. Tegetmeier observed that a game cock, dis- 

 figured by being dubbed and with hackles trimmed, was accepted 

 by the females. 



Mayer has recently carried out some experiments with the 

 moth Callosamia promethia that show very clearly that the 

 adornment of the male or of the female is not a factor in the 

 selection by the other sex Five females were placed in an open- 

 mouthed glass jar covered by netting. Five males, liberated one 

 hundred feet away, flew to the jar. If the jar was inverted so 

 that its opening was closed, the males did not approach, although 

 the females could be seen through the glass. It appears, there- 

 fore, that the males find the female by the sense of smell, not by 

 sight. 



Some females were inclosed in a box with an open chimney. 

 The mates flew to the chimney, although the females were not 

 visible. When the abdomen of the females were cut off the 

 males flew to these, and paid no attention to the winged body. 

 Wherever a female has stood for some time, the males are at- 

 tracted to that spot. If the antennae of a male are cut off, he 

 does not go to the female. These experiments also show that 

 the male finds the female by a sense of smell, and not by 

 vision, although the female is highly ornamented. 



