SECONDARY SEXUAL CHARACTERS 103 



their ornaments before a female bird. One would 

 shoot up like a rocket, then, suddenly expanding the 

 snow-white tail like an inverted parachute, slowly 

 descend in front of her, turning around gradually to 

 show off both back and front. The expanded white 

 tail covered more space than all the rest of the bird, and 

 was evidently the grand feature of the performance. 

 Whilst one was descending the other would shoot 

 up and come slowly down expanded." 



There is just a suspicion in my. mind that these males 

 were otherwise engaged, for while I know nothing 

 about the habits of these humming birds I find on the 

 next page of " Tropical Nature " this statement : 



^'Mr. Gosse also remarks: ^All the humming- 

 birds have more or less the habit, when in flight, of 

 pausing in the air and throwing the body and tail into 

 rapid and odd contortions. This is most observable 

 in Polytmus, from the effect that such motions have 

 on the long feathers of the tail. That the object of 

 these quick turns is the capture of insects, I am sure, 

 having watched one thus engaged.' " 



If what I have just said implies that I take a light- 

 hearted or even facetious attitude toward Darwin's 

 theory, I trust that my position will not be misunder- 

 stood. Darwin brought together in his book on the 

 ^'Descent of Man" a mass of interesting observations 

 for which he suggested a new theory. No one can 

 read his wonderful book without the keenest interest, 

 or leave it without high admiration for the thorough- 

 ness with which the subject is treated ; for the ingenuity 

 and skill with which the theory is applied to the facts, 

 and, above, all, admiration for the moderation, modesty, 



