152 THE LIFE OF A BIRD. 



The numbers in the first column denote the 

 mean number of eggs for the family ; those in 

 the next, the most common next number ; and in 

 the third, the limit either at which they commence 

 or terminate. 



On casting the eye over these figures it is diffi- 

 cult to detect anything like an established rule or 

 set of rules, according to which the numbers of 

 eggs are distributed. Certainly these figures do 

 not discover to us the principle upon which this 

 allotment is based. Yet we perceive something of 

 a law, which has received the assent of naturalists, 

 without much inquiry as to its correctness. It has 

 generally been said that the number of eggs pro- 

 duced by birds increase in proportion to the dimi- 

 nishing size of the mother. The wren, for example, 

 produces from seven to eight eggs, according to 



* Exception, Swan, 3. t Exception, Gannet, 1. % Exception, Petrels, 1. 



