196 DARWINISM AND THE PROBLEMS OF LIFE 



enchantment of the females, and we are faced again 

 with a problem that we cannot solve. In this case 

 there is less objection than elsewhere to the second 

 form of sexual selection. It is not called upon to 

 explain the origin of the perfumes, but only its increase 

 in the male sex. The odour certainly came into 

 existence as a distinctive mark of the species, as it is 

 also found in the female sex, though in so weak a 

 form that our nose cannot perceive it. But it can 

 easily be proved to be present by placing a female of 

 some species of night -butterfly in a wire box before 

 the window. A number of males will presently be 

 found in it, and they can only have discovered by 

 smell the presence of the object of their desire. 

 Hence if a female knows the odour as a mark of the 

 species, it will be much more affected by it when 

 its strength increases. Possibly this is the root of its 

 advancement. 



The union of the 'sexes is sometimes stormy among 

 the insects. The females of the large dragon-flies often 

 fly in obvious fear from their spouses. In the case of 

 other insects it is the male that must be careful. It 

 happens only too often that the love-sick male cricket 

 is devoured by the callous female. In fact, in the case 

 of the mantis or praying insect, a green locust whose 

 front legs are lifted up as if in prayer, though they are 

 really only for the purpose of grasping its prey, the male 

 is generally devoured during, but at least always after, 

 union. It has even been observed in the case of this 

 species that the female bit the head off the timidly 

 approaching male ; the trunk, nevertheless, performed 



