ON GENERATION. 229 



The shell, already less transparent, becomes dingy. 



The albumen grows thicker and more viscid, and acquires a 

 straw or yellow colour. 



The tunica propria of the vitellus becomes more lax, and 

 appears wrinkled, for it seems that some even of this fluid is 

 dissipated in the course of time. 



The chalazse are found in either end of every egg, in the same 

 situation, and having the same consistence whether the egg be 

 recent or stale, fruitful or barren, it does not signify ; by their 

 means a firm connexion is established between the yelk and the 

 white, and the two fluids preserve their relative positions. The 

 chalazse, indeed, are two mutually opposed supports or poles, 

 and hinges of this microcosm ; and are constructed as if made 

 up of numerous coats of the albumen, twisted together at either 

 end into a knotted rope, by which they are attached to the 

 vitellus. And hence it happens that the yelk is separated from 

 the white with difficulty, unless the chalazse are either first di- 

 vided with a knife or torn with the fingers ; this done, the white 

 immediately falls away from the yelk. It is by means of these 

 hinges that the vitellus is both retained in the centre of the 

 egg and preserved of its proper consistence. And they are 

 so connected that the principal part, the cicatricula, to wit, 

 always regards the same region of the egg, or its upper part, 

 and is preserved equidistant from either end. For this spot or 

 cicatricula is observed to be of the same consistence, dimensions, 

 and colour, and in the same situation in the stale as in the new- 

 laid egg. But as soon as the egg, under the influence of the 

 gentle warmth of the incubating hen, or of warmth derived from 

 another source, begins to pullulate, this spot forthwith dilates, 

 and expands like the pupil of the eye, and from thence, as the 

 grand centre of the egg, the latent plastic force breaks forth and 

 germinates. This first commencement of the chick, however, so 

 far as I am aware, has not yet been observed by any one. 



On the second day of the incubation, after the egg has been 

 exposed to warmth for twenty-four hours, under the hen, as 

 the cavity in the blunt end has enlarged greatly and descended, 

 so has the internal constitution of the egg also begun to be 

 changed. The yelk, which had hitherto lain in the middle of 

 the albumen, rises towards the blunt end, and its middle, where 

 the cicatricula is situated, is lifted up and applied to the mem- 



