Cuap. II. ALBUMEN AND EGG SHELL. 508 
trates, inasmuch as upon opening these eggs nothing but a thin, hardly consistent, 
jelly-like albumen pressed its smooth surface against the closely embracing shell 
membrane. 
From the foregoing facts, it is evident that the concentric layers of albumen 
are not deposited by direct apposition of the glandular wall of the oviduct upon 
the yolk sac; so that, whatever turns the egg may make in its passage along 
the channel of the latter, this glairy envelope is not impressed with such a spiral 
arrangement of its strata as constantly obtains in that of Birds; consequently there 
are no chalaze. Again: we may justly infer from this structure that there is no 
spiral motion of the egg, in its descent from the inlet to the outlet of its con- 
duit, otherwise a simple inversion of the egg would not injure its contents, as 
experience has shown to be the case when inadvertently a Turtle was opened 
whilst laying upon its back, and the eggs were taken out in this abnormal posi- 
1 whereas in the albumen of Birds the chalaze are formed early, and serve 
tion ; 
as axles, upon which the yolk sac swings and keeps its embryonic side upper- 
most, whilst the more exterior albumen revolves about it. Except to mention that 
the whole albumen is deposited before the calcareous deposition commences, we 
will defer any general remarks in reference to the shell until we come to describe 
its microscopic structure. 
What we have just shown in regard to the albumen, the shell lining, and 
the shell deposit, leads very naturally to the question, What is the essential differ- 
ence, between the mode of formation and the structure of these concentric layers, 
which renders them so distinct from each other, and how can they all be the 
product of one and the same portion of the same organ? The only reply we 
can make to the latter part of this question is, that it is just as possible for one 
organ, more or less complicated, to perform diverse functions, as that so simple a 
structure as an ego can produce, within itself, the multitude of functions which 
constitute the organic whole of an independent animal; but how this is done still 
remains among the mysteries inaccessible to our investigations. As regards the 
first part of the question, we will endeavor to answer it so far as our observa- 
tions may guide us. We have already proved, by direct ocular demonstration, that 
the greater part, and, we would suggest, perhaps the whole, of the albumen is at 
times, if not always, deposited by infiltration through the already partially formed 
and synchronically developing shell-lining membrane. Now, notwithstanding this sub- 
stance enters the confines of the linmg membrane in a fluid state, yet it by no 
means continues in this condition, nor does it remain simply, as at the first glance 
it seems to be, a gelatinous, homogeneous bed, in which the yolk rests. 
? On that account, Turtles ought always to be opened from aboye to examine the eggs. 
