COLOURS PRODUCED BY COURTSHIP 289 



keenness of the males in pursuing the females is so 

 well known and remarkable. 



In spite of this very exceptional keenness in the 

 wild state, my friend Dr. Dixey found in two succes- 

 sive years that it is by no means easy to pair them, 

 when both males and females are bred in captivity. 

 I have had exactly the same experience with the con- 

 tinental Tau Emperor (Aglia tau), although the 

 wonderful antennae of the male show that the powers 

 of this species are even more intense than those of our 

 own Emperor Moth. If there is such a marvellous 

 change in the disposition of these species, it is at least 

 j)robable that similar changes occur in other species 

 with more phlegmatic males. The difficulty with 

 which the great majority of butterflies and moths can 

 be induced to pair when bred in captivity (although 

 captured females, already fertilised, will generally 

 lay eggs), and the fact that an increased chance of 

 success is afforded by imitating the natural conditions 

 as far as possible, point in the same direction. 



The argument applies with even greater force to 

 many of the higher animals. The effect of domestica- 

 tion upon the brain of the domestic duck has been 

 proved in the most striking manner by Sir James 

 Crichton Browne.^ The comparison between twenty 



* The interesting facts and conclusions summarised on p, 290 were 

 contained in a paper read at the meeting of the British Association 

 at Sheffield in 1879. The paper has never been published, but Sir 

 James Crichton Browne has kindly allowed me to use the manu- 

 script. 



