CHAPTER II. 



Any one who is conversant with Yarrell's admirable " British 

 Birds," will most likely have noticed that that author gives 

 in almost every case very precise measurements of the eggs 

 of each particular species of Bird described. And it might, at 

 first sight, seem to be so necessary to give such measurements 

 that one would very likely feel half inclined to pronounce a Book 

 of Birds* Eggs very imperfect, which omitted all notice of 

 dimensions. But the fact is, such measurements are, in so very 

 many different instances, altogether fallacious and likely to 

 mislead. Thus Mr. Yarrell's measurements of the Blackbird's 

 egg are, " the length one inch, two lines ; the breadth ten lines." 

 That is no doubt a good average or approximate measurement, 

 but I have Blackbirds' eggs betore me which vary between half 

 a line, or ^ of an inch, less, and a line, or T V of an inch, more 

 in length, and between half a line, more or less, in breadth. Again, 

 I have two Starlings' eggs on my table, both taken from the same 

 Pigeon-cote, in Essex ; one of which is 1 3 9 ^ inch long by %% inch 

 broad ; the other 1 3 % inch long, and f inch broad; while to the 

 eye the latter is not much more than half as lame as the 

 former. Moreover, Mr. Yarrell's measurements for this bird's 

 eggs are precisely the same as for those of the Blackbird, and not 

 only not tallying with those of either of my eggs, but not even 

 presenting a near approach to the medium dimensions. 



Great numbers ol similar instances might be adduced, 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 comparison with, the others as to set one invariably 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 

 or 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 

 past effects of injury or sickness, by a partial failure of some 

 necessary element of food, by undue pressure on the egg-pro- 

 ducing 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 



