in the fixed principles of the egg during incubation. 389 
The consideration of the organization, See. of the incubated 
egg, like that of its constituent principles, does not fall within 
my present design ; yet, as some points connected with these 
subjects seem to be illustrated by the present inquiry, and as 
my experiments would be scarcely intelligible without them, 
I shall make a few brief remarks on the general phenomena 
presented by the different constituent principles of the egg at 
those periods at which it has been submitted to examina- 
tion. 
It has been remarked by many observers, that soon after 
the process of incubation has commenced, the yelk becomes 
more fluid than usual, and that as the liquor amnii increases, 
that portion of the albumen occupying the upper and larger 
end of the egg, begins to assume a peculiar appearance. In 
the present experiments (in which the egg was always pre- 
viously boiled), the liquor amnii and portion of albumen in 
question, at the period now under consideration, exhibited 
somewhat the appearance of curds and whey. Nor did the 
analogy consist in mere appearance ; for the curdy looking 
matter, which was of a yellow colour, and which I have 
termed 7 nodified albumen, resembled the curdy part of milk in 
its properties, so far as to contain intermixed with it an oily 
or butyraceous principle. A portion of this oily principle, on 
being separated and examined, was found to be soluble in 
alcohol, of a bright yellow colour : and in short, to possess 
all the properties of the yellow oil existing in the yelk. The 
yelk at this period, as before observed, has become more 
fluid, and appears larger and of a paler colour than natural , 
Haller, indeed, asserts, that it has not increased in weight, 
but the above table renders the reverse very probable. These 
appearances of the albumen and yelk have induced most 
