246: DR. CARUS ON THE KINGDOMS OF NATURE, 
carbonic acid gas, with the additional one of nitrogen, which peculiarly 
belongs to this kingdom, and the volatile nature of which perfectly 
agrees with the rapid merging of animal bodies in the universal life of 
nature, as soon as their individual life is extinct; to which passage, 
however, the earthy parts, such as bones and shells, offer somewhat 
longer resistance. In regard to the internal formation of the solid parts 
of the animal body, it has been already remarked (see p. 244) that the 
spherical type, in so far as it is peculiar to animal forms in general, is also 
visible in the basis of all animal matter, so that the molecular substance 
is the basis of the collective animal body. If we now reflect likewise 
how in the Infusoria and Priestley’s matter, the rudiments of the animal 
kingdom appear as so many animated globuli, we shall thence perceive 
that the largest animal bodies themselves must be viewed as an innu- 
merable aggregate of Infusoria, but at the same time united into a living 
whole. It is moreover worthy of remark, that very essential differences 
present themselves in respect to the primary formation of the animal 
body in its different systems. It is also a remarkable fact, that in the 
organs exclusively proper to the animal,—for instance, in those of sense, 
motion, and the nerves,—this molecular mass is clearly discernible, partly 
as the marrow of the nerves (a peculiar grey substance), partly as de- 
veloped nervous and muscular fibres ; while in the organs which are 
more immediately borrowed from the plant (the vascular system, the 
skin, and the intestines), we remark again a very decided tendency to 
cellular formation. 
We have now before us two modes of perceiving in its true nature the 
further formation of the primary animal mass into the single organs of the 
animal body; either that of attentively watching the development of one 
complete animal organism in its different stages, or that of observing 
the succession of the species according to the order of animals in the 
development of their animalism. Of these two we shall give only the 
principal outlines of the first series of formation*, in which we shall find 
a great analogy to the development of the plant, but more especially 
a manifold confirmation of that which we have advanced in regard to 
the metamorphosis, or rather elevation, of vegetable into animal life. 
But in tracing the development of the individual animal body through 
its several stages, we shall take as the main object of our observations the 
human organization as the most perfect ; and thus we shall have occa- 
sion to recur to that of other animals in those cases only in which the 
observations made on the human being itself are deficient in regard to 
its first rudiments. 
* The observation of the development of organization in the series of ani- 
mals, is the idea upon which Carus’s Manual of Zootomy is founded, to which 
he here refers his readers. 
