J A MES NE WTON BA SKE TT. 103 



Just what this stimulant is we may never know. That it 

 is dependent in some measure on food is probable, and that 

 climate affects egg-colors is certain ; but in what way is the 

 question. The coloring matter has been thought to be 

 closely connected with the waste products or coloring of the 

 blood and bile. In the one case the bird may be putting on 

 ashes for beauty merely, and in the other she may be like 

 the rest of us — stimulated into her best work or hampered 

 into her worst by the " condition of her liver."' 



Perhaps it is scarcely necessary to say that there is no 

 relation between the color of a bird's plumage and its eggs. 

 The Peacock and the Humming-bird in all their gaudiness 

 lay plain white eggs. 



A few thoughts now about shape and I am done. Natu- 

 rally, if left to itself, the shape of the egg would be globular, 

 because before the shell is hardened it is fluid. In the 

 reptiles it is said always to be globular or ellipsoidal. The 

 last condition is doubtless brought about by compression ; 

 and in some serpents, perhaps on account of close quarters, 

 the shape is much elongated. 



Birds inherited these shapes from the reptiles. In many 

 of them the globular and the ellipsoidal shapes yet prevail 

 — especially in the lower forms. But in most birds there 

 is a distinct ovoid shape, with one end smaller than the 

 other. 



We know not what has brought about the various forms 

 in birds' eggs, but the impression is strong that the ovoid 

 shape is in some way connected with incubation and pos- 

 sibly with upright or bipedal posture. The best illustration 

 with regard to its correlations with incubation is seen in some 

 of the narrow-breasted Plover-forms, where the number of eggs 

 is usually three, or oftener four, with very sharp points at one 

 €nd ; and they are found in the nest with the points toward 

 the centre. It is of record that if disarranged the bird 

 turns the points all inward before " going on " again. 



In some Gulls similar eggs are found on one side of this 



