122 HABITS OF BIRDS. 



bluish white, and marked at the larger end with a 

 zone of irregular reddish streaks, the other about a 

 third smaller, quite spotless, not the slightest marki-n< 

 being perceptible. We infer that these appearances 

 were in consequence of this egg being too small 

 either to stimulate the glands to secrete, or to press 

 them to give out their colouring matter*. 



This, if correct, as it appears to be, will account irt 

 a satisfactory manner for the great diversity of mark** 

 ings in eggs belonging to the same species, and even 

 to the same bird. " The eggs of birds," says Mr. 

 Knapp, " in general vary much, and are occasionally 

 very puzzling to identify, when detached from their 

 nests, as the colourings and markings differ greatly 

 in the same species, and even nest. Those of one 

 colour retain it, with only shades of variation ; but 

 when there are blotchings or spots, these are at times 

 very dissimilar, occasioned, in great measure, pro- 

 bably by the age of the bird ; though this cannot 

 account for the difference of those in an individual 

 riest. Those of marine birds, especially the guillemot 

 (Colymbus Troile) are often so unlike each other, 

 that it requires considerable practice to arrange 

 them-j-." He adds, " that though the marks are so 

 variable, yet the shadings and spottings of one species 

 never wander so as to become exactly figured like 

 those of another family, but preserve, year after year, 

 a certain characteristic figuring." 



This is indeed generally true, although the eggs of 

 the goldfinch and the chaffinch frequently exhibit 

 nearly the same markings ; and we have seen more 

 than one egg of the chaffinch so like in marking to 

 those of the yellow-hammer that they could only 

 be distinguished by an experienced eye}. The eggs 

 of the house-sparrow, as Mr. Knapp remarks, are 



* J. R, f J( > urn of a Nat. p, 224, J J. R, 



