THE SEXUAL SELECTION THEORY 147 



The existence of this nexus of conditions is commonly 

 overlooked, but it is extremely important. Normally, 

 not only among birds, but other animals higher and lower 

 in the scale of life, " suggestion " does not suggest until 

 the " hormones " concerned with the sexual activities 

 have, as it were, saturated the system and rendered it, 

 so to speak, highly inflammable. Even then it commonly 

 happens that, with the male at any rate, this inflammable 

 state bursts into flame of its own accord. But for this 

 indeed, how could the consummation of the period of 

 sexual activity ever be realized ? In many cases the 

 sexes are sundered far apart. What, but the merest 

 accident, could bring them together if it were not for this 

 consuming fire of desire which impels each sex to seek out 

 the other ? This stage is manifested in the case of the 

 Deer, where, we have seen, the stag wanders far and wide 

 bellowing to advertise his errand and listening for a 

 response to his call. He is possessed by a " mate-hunger " 

 which eventually attains to a state of frenzy. Here no 

 " suggestion " is needed, but the necessity for this stimulus, 

 for some form of aphrodisiac, occurs with him after 

 the first relief of his pent-up state has been attained. 

 This stimulus is applied, both through the eye and the 

 sense of smell, by the females of his herd. The same 

 conditions apply in the case of the birds. But it is to 

 be noted that with the females, as in the case of mammals, 

 sexual desire is commonly less intense than in the males, 

 and hence, in their case the need for " suggestion " by 

 display of some sort. But apart from this, a " display " 

 of some kind is necessary. How else can desire be 

 indicated ? And here is " sexual selection." For males, 

 mate-hungry as they might be, which resorted to no 

 means of expressing their condition would go mateless : 



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