10 THE COURTSHIP OF ANIMALS 



follows her mate in the acquisition of new characters 

 is, so to speak, set aside. She follows a line of her own. 

 This is true, at any rate, of superficial characters, 

 such as coloration. By some curious change in her 

 " metabolism," as the conversion into living tissue of the 

 substances taken as food is called, this coloration may 

 attain a brilliance in no way inferior to that of the male, 

 but strikingly different. The beautiful Orange Fruit- 

 pigeon {Chrysoenas victor) furnishes a case in point, the 

 male being of a gorgeous orange-yellow, the female of 

 a no less vivid green. But the differences are not so 

 great as they appear at first sight. For the male was 

 originally green, and the female has thus but intensified 

 the ancestral livery. Green, it should be remarked, of 

 a more or less olive shade, always precedes yellow in 

 development ; and yellow may yield to red, but this order 

 is never reversed. A no less striking case is that of the 

 Upland Goose {Cloephaga magellanica), the male of which 

 is pure white, while the female wears a livery of chestnut 

 and brown. But so sharply are the colours defined 

 that it would be difficult to say that one was of a higher 

 order of coloration than the other. To what caiises or 

 factors are these departures due ? 



Reproduction in the simplest living things takes place 

 by a simple division of the body into two as soon as its 

 maximum size or adult condition has been attained. 

 In such simple types the body consists only of a single 

 " blob," or particle, of jelly. But a new era began when 

 large numbers of such particles, or " cells," began to 

 form coherent masses, different parts of the mass per- 

 forming different work for the mutual benefit of the 

 community. Some have come to form what we call the 

 body, which is born, and in due course dies. Others are 



