TJieir Eggs and Nests. 1 3 



bird, and not only not tallying with those of cither of 

 my e^^gs, but not even presenting a near approach to 

 the medium dimensions. 



Great numbers of similar instances might be ad- 

 duced, and in connection with the very commonest 

 birds. Even eggs from the same nest may continually 

 be met with, presenting great disparity in bulk ; one 

 in the number being frequently so small in compari- 

 son with the others, as invariably to set one thinking 

 it must have been the last laid, and that a partial 

 failure of egg-producing power in the mother-bird 

 must be the explanation of the phenomenon. 



It seems scarcely open to question that the physical 

 condition of the parent-bird must exercise a great 

 influence over its egg-producing capacity. Its powers 

 may be impaired by age, by the effects of recent 

 injury or sickness, by a partial failure of some neces- 

 sary element of food, by undue pressure on the egg- 

 producing organs, such as must occur by the loss of 

 one or more early layings. Indeed all these causes are 

 well known to interfere with the reproductive energies 

 of animals at large, and it is a thoroughly ascertained 

 fact that both the first and the last act most strongly 

 in the case of many birds. The comparative size of 

 birds' eggs, therefore, seems to me a matter to which 

 it is unnecessary, if not inexpedient, to direct the young 

 collector's attention ; in any other way, at least, than 

 as to a matter of curious observation and contrast. 

 As a means of identification it fails completely, and is 

 only adverted to here for the purpose of obviating a 

 portion of the perplexity which may often occur in 

 practice to the youthful egg-fancier from the differ- 



