ON THE EGG. 261 



the plaster having thoroughly and firmly set, the shell is formed 

 and the egg is completed, and is thrust down into the receiving 

 pouch beneath, and is ready to be laid. 



Now, it is during the third part of this truly wonderful pro- 

 cess — the egg-forming — that the coloration and the exact form 

 of the exterior of the egg are determined. The shell is generally 

 smooth on the surface, but the cormorant's white eggs are rough, 

 and long and narrow, "When the egg is smooth and slender, 

 and the oviduct moderately excited and vascular, the egg may 

 pass easily down the oviduct and be laid pure white. Some few 

 are quite as if polished. The uniform ground colour of eggs, 

 whether these are spotted or not, is owing to the state of the 

 circulation and innervation of the mucous membrane of the ovi- 

 duct at the time the egg is passing down the third part of the 

 oviduct. If that part be congested at the time, the liquid plaster 

 may be tinged more or less deeply with blue — pale as in the egg 

 of the heron and kingfisher, darker as in that of the hedge- 

 sparrow, thrush, and starling. If more congested or inflamed, 

 the plaster may get a yellow tinge as in the egg of the grebe ; 

 a green in the emu, or a pink tinge ; in a still higher degree 

 of congestion the egg may be stained less or more with red, and 

 blood be effused in varying quantity, forming spots or blotches 

 in some cases almost covering the whole surface of the egg, and 

 patches assuming even a black colour, as in most of the eggs of 

 the Falconidse. If in addition to the quasi-inflammatory state 

 (which is evanescent) of the mucous membrane, if the egg be 

 bulky and the blood vessels numerous and turgid, and the grip 

 of the egg by the muscular wall of the oviduct be tight, one or 

 more of the blood vessels may be wounded, and the blood escap- 

 ing, must fall on the abrading part of the egg, giving rise to 

 one or another form of spotting or streaking or blotching. And 

 this may occur either with white eggs or with those of any 

 ground colour, as we find in nature. Spots that are round have 

 been deposited when the egg was not moving, streaks when the 

 egg has been moved by the contraction of the muscular wall in 

 various directions, and it is apparent that, from the evidence to 

 be gathered from some eggs, as those of the crane, snipe, sand- 



