396 Darwin, and after Darwin. 



so exclusively related to the sexual relationship on the 

 other. 



Finally, we must take notice of the fact that where 

 peculiar structures are concerned for purposes of dis- 

 play in courtship, the elaboration of these structures is 

 often no less remarkable than that of patterns where 



ADULT MULE 



FIG. 124 The Bell-bird (Chasmorhynchus niveus, natural size). 

 Drawn from nature (R. Coll. Surg. Mus.}. In the drawing of the 

 adult male the ornamental appendage is represented in its inflated 

 condition, during courtship ; in the drawing of the young male it is 

 shown in its flaccid condition. 



colours are thus concerned. Take, for example, the case 

 of the Bell-bird, which I select from an innumerable 

 number of instances that might be mentioned because, 

 while giving a verbal description of this animal, 

 Darwin does not supply a pictorial representation 



