200 GENERATION. 



the Bird we are here describing, it is only necessary to understand the 

 structure of the egg of tbat order of animals. 



The mass of an egg is composed of two parts, the orange -coloured 

 part, called the yolk, and the transparent surrounding part, called the 

 ' white' or ' albumen :' but this term is only applied to its turning white 

 upon coagulation ; but as it has all the characters of a mucus called 

 slime, I shall call it the slime. The yolk is a portion of the ovaria, or 

 formed by it ; which is what I shall first consider. 



The ovarium in the Bird is in one of two states : one is the quiet or 

 [unexcited] state ; the other is the state for impregnation. In the first 

 the ova are small, like millet- seed, composed of a little bag filled with 

 a yolk in miniature. They are formed in a cluster in the loins of the 

 Bird, upon the vena cava, as if formed upon it or growing out from it, 

 so as to be inseparable. These small bodies are of different colours in 

 different birds, and sometimes different iu the same bird. As the consti- 

 tution is changing towards propagation, these little bodies begin to swell, 

 by becoming fuller of the matter of the yolk. Some advance faster than 

 the others, in a kind of regular gradation, forming regular series. As 

 they advance they become attached by a neck, which is small and pretty 

 long in some. Their capsule becomes extremely vascular, more espe- 

 cially the veins, wbich run from the neck as a centre, and spread in a 

 radiated form on the membrane, and then, as it were, converge on the 

 opposite side. "When nearly arrived at full size, an oblong part of the 

 capsule becomes very thin, and the yolk can be seen through it. This 

 gives way and it opens, through which the yolk makes its escape. At 

 this very period we must suppose that the mouth of the oviduct is so 

 placed as to catch it, along which it passes. 



The yolk is in the centre of the slinie, seen through it, as it were 

 swimming in it. It is round, and is lighter, in the whole, in weight than 

 the slime, so that it always rises towards the upper side of the egg ; but 

 it is not in equal weight in itself through the whole, one side being 

 lighter than the other, which side always keeps uppermost, let the egg 

 be ever so often turned ; like the needle to the pole, let the compass be 

 ever so often turned, the point of the needle keeps to the pole. On this 

 side is the cicatricula, in which the chick is formed ; therefore it is 

 always nearest the heat of the mother, although the chick is of more 

 condensed materials, and therefore one would suppose it would destroy 

 this quality on this side of the yolk ; yet we find it does not, for this 

 side keeps uppermost till the chick almost fills the whole space or shell, 

 and therefore cannot turn, and now it is not necessary it should. It 

 [the yolk] is of the consistence of thick cream, and is eoagulable with 

 heat, solutions of alum, alcohol, goulard, etc. 



