578 EMBRYOLOGY OF THE TURTLE. Part III. 
d) are perhaps as much ossified as those of the vertebral column. The bones of 
the toes come next in the series, the ossification here being principally along the 
cylinder. The other bones of the limbs are much less ossified. The ribs have 
already a broadly winged margin (PI. 9e, fig. 12, 6); there is only a thin layer 
of bony substance at the surface, near the base of attachment to the vertebre ; 
the rest of their length is densely fibrous, (Pl. 9e, fig. 12, 6 to 6; Pl. 22, fig. 1, 
b, c, d, e, fig. 2, ¢, d, e, f,) with a cartilagmous interior (Pl. 9e, fig. 12, a, a; Pl. 
22, fig. 1 and’ 2; a, a’, a*, a’). “The skin, corium; (Pl. Qe, fig. 12, ¢ es PL 23, 
fig. 4, 6, 7, 8, 10; and w-c. 6, 7, w-e. 7, 4 w-e. 8, g, w-c. 10, g,) is a very dense 
layer of thickly matted, fine, white fibres (Pl. 22, fig. 1, g, go’, h, W); it is 
thickest between the ribs. Throughout its thickness there are scattered groups of 
pigment granules, and a short distance below the epidermis there is a dense, uni- 
form layer of these pigment granules, (Pl. 9e, fig. 12, 4,) which seems to be a 
dividing lime between the corium (fig. 12, gy) and the epidermis; but this is not so, 
for the epidermis (Pl. 20, fig. 18) is a very thin film, here (Pl. 9e, fig. 12) rep- 
resented by a black line, between which and the pigment stratum there is a mod- 
erately thick layer of fibrous substance, (fig. 12, 7) which, to all appearances, is 
identical with, and merely a continuation of, the corium. 
This is sufficient, in a general point of view, to characterize the young Turtles 
at the time of hatching; especially if, to avoid repetition, we refer to a previous 
section, (Part IL, Chap. 1, Sect. 14, p. 290,) on the development of Turtles from 
a zodlogical pomt of view, and to another, (Part IL, Chap. 3, Sect. 4, p. 386,) 
on the comparison of the growth of the Chelonii with that of the Amydez, in 
which the young of several species, belonging to different families, are described 
at that age. In the next section, further details concerning the development of 
several organs will be given, and this, with the section on the Histology of 
the embryo, will complete the account of our observations respecting the origin 
and mode of growth of the Turtles. One single general remark, however, may 
with propriety find place here, before we proceed to these specialities. 
The great wonder, in the development of all organized beings, consists in the 
differentiation of the substance in the different parts of the same body, while it 
remains under identical influences. This evidently takes place under the action of 
that principle, in virtue of which every animal is an individual of some special kind 
of animals, and not in consequence of any physical agency. The living egg makes 
its own different substances because it lives, and not in order that a new animal 
may grow up. This has an important bearing upon the general question of the 
nature and origin of matter. Without approaching this subject in detail, I would 
only express my belief, that matter does not exist as such, but is everywhere 
and always a specific thing, as are all finite beings. 
