188 Mr. A. G. Mayer on the 



pliotograpliic paste ^, he no longer seeks the female, and 

 displays no excitement even though within an inch of her. 

 In five instances I removed the paste by dissolving it in 

 water, and in four of these cases the males readily mated with 

 the females. Upon again covering the antennae with the 

 paste the males again failed to notice the females when in 

 close proximity to them. 



There can be but little doubt that the organs by which the 

 male perceives the female are situated in theantennte; indeed 

 it has long been recognized that the olfactory organs of insects 

 are found chiefly upon the antennae. Hauser (1880) and 

 Kraepelin (I880) have given excellent descriptions of the 

 minute anatomy of these organs, Hauser having carried out 

 an elaborate series of physiological experiments to determine 

 their functions. He cut off the antennee of several species of 

 insects and found that their sense of smell was then either 

 greatly impaired or totally lost; covering their antennge with 

 melted paratfin gave the same results. 



Hauser also found that when the antennjfi of the male 

 {Saiiirm'a pavonia) were removed the moth never makes any 

 attempt to mate. 



Packard (1898) gives an excellent review of all researches 

 relating to the anatomy and physiology of the olfactory organs 

 in insects. 



If the eye of a male {CaUosamia promethia) be covered 

 thickly with pitch or Brunswick black f, so as to preclude the 

 possibility of sight remaining, the male will still mate in a 

 normal manner when placed near the female. 



It will be remembered that in this moth the male is black 

 while the female is reddish brown ; in accordance with the 

 well-known theory of Darwin, the peculiar coloration of the 

 male might be due to sexual selection on the part of the 

 female. We might suppose, indeed, that the female preferred 

 dark-coloured males, and thus under the influence of sexual 

 selection the males became darker and darker, until the present 

 melanic colour has been attained. 



In 1897 the author showed that the melanic colour of 

 the male of this moth is phylogenetically newer than the 

 colour-pattern of the female, and this fact, so far as it goes, 

 lends support to this theory of Darwin's. 



In order to test this hypothesis I cut off the wings of a 

 number of females, leaving only short stumps, from which all 



* The photographic paste mentioned was " Stafford's white paste " ; 

 probably any impervious paste would serve as well. 



t This substance is commonly used as microscopic cement, and is of a 

 pitchy consistency and a dense brown-black colour. 



