THE CYCLE OF LIFE 



413 



weak, the cowardly, the clmnsy, the dull, and so on, so 

 that they are definitely unsuccessful or less successful in 

 reproduction, the combats of the naales will probably have 

 some direct evolutionary influence, as Darwin confidently 

 believed. But there is great need for a stern sifting of the 

 data and an accumulation of more. 



On the other side, there is the great variety of peaceful 



Pig. 63. — Male spider (Icius mitrahis) dancing. {After Peokham.) 



ways in which male animals give expression to their emotions 

 in the presence or proximity of their desired mates. Many 

 male spiders have a characteristic love-dance, differing 

 for different species, in which they appear to our eyes as 

 if they were showing off their good points. Some insects 

 have luminous love-signals, many offer up fragrant incense, 

 many give themselves up to energetic serenading — ^if we 

 may so call it in our almost complete absence of knowledge 

 in regard to the sense of hearing in insects. Many birds 

 make elaborate displays, bending and bowing, strutting 

 and saluting, circling and fluttering ; and even a few of the 



