392 Dr. Prout’s experiments on the changes which take place 
How the above interchange of principles takes place be- 
tween the albumen and yelk, does not appear to be distinctly 
understood. Maitre Jean, Leveille, and others, suppose 
that it takes place through the chalazce ; and Leveille has 
even pretended to demonstrate the tubular structure of one 
of the chalazae. This tubular structure has been denied by 
some writers, and particularly by Dr. Macartney,* who 
even appears to doubt the fact of the intermixture in ques- 
tion. After what has been said, however, there cannot, I 
think, be much doubt of the circumstance ; and future in- 
quirers on this interesting, but difficult subject, will do well 
to turn their attention to it. 
Experiments on the egg at the end of the second week , or about 
the 15th day of incubation. 
At the end of the second week of incubation, an egg has 
lost upon an average about 130 grains, on the supposition 
that its original weight was 1000 grains, and the weights of 
the constituent principles of two eggs were as follow : 
Unchanged Albumen 
Grains. 
^ 75-5 
Grains. 
208.0 
Liquor amnii, membranes, &c. 
2735 
2l8.2 
Animal .... 
70.0 
89.I 
Yelk .... 
230.7 
248.O 
Shell and Loss 
230.3 
236.7 
1000.0 
1000.0 
At this period the animal has attained a considerable size, 
while the albumen has become diminished in a corresponding 
* Article Incubation, in Rees’s Encyclopcedia. 
