THE PRINCIPLE OF VITAL AFFINITY. 177 
consolidation, not precipitation, just as the fibrin of the blood, differing from the 
albumen only in its stronger (vital) tendency to aggregation, is consolidated in 
its compound form from the liquor sanguinis in the act of coagulation. And thus 
it happens that these organic solids possess (as was particularly noticed by Dr 
Prout) that peculiarity which, in the inorganic world, is observed only in fluids, 
that even the minutest portion of them contains the very same ingredients 
(whether earthy or saline, animal or vegetable matters) as is found in the whole 
mass. 
The absence of all crystalline arrangement, and the complex nature even of 
the smallest particle of an organized body, are the characteristics of matter 
which has assumed the solid from the fluid form,—not by a chemical precipita- 
tion, or separation from matter formerly united to it, but by a vital attrac- 
tion, subjecting it to “the invisible cause by which the forms of organs are 
produced.” 
4, In the next place, we may inquire what difference exists among the cells 
in different parts of the same structure, to explain the great difference of the 
compounds which are deposited in them from the same nourishing fluid; and I 
apprehend, that, on this point, we must come to the same conclusion which 
Cuvier drew from examining, throughout the animal kingdom, the structure of 
the different glands, the vessels entering them, and the ducts passing out of them, 
viz., that there is no difference of structure or of composition, corresponding, in 
the slightest degree, to the great difference of the products which appear. All 
cells, in the vegetable kingdom, appear to consist of the same matter, cellulose, 
and in the animal kingdom of the same matter, protein ; and in the first instance 
they are quite similar to one another. When we attend to the early stages of 
the existence of a living body, when the difference of textures is only beginning 
to appear, we find only that a fluid passing through similar capillary vessels, and 
effused into similar cells, in different parts of the structure, acquires different 
properties. And when we carry our inquiries farther back, and observe the first 
development of cells themselves out of the granular matter inclosed within the 
sac of the yolk, it appears obvious that the particles of this matter are attracted, 
not into cells already existing, but to points where cells are about to be formed. 
The facts known as to the evolution of the chick in ovo from the matter that 
lies in contact with the germinal membrane, sufficiently indicate that the powers 
which effect the separation of the different component parts of that matter, so as to 
form the beginning of the different textures and organs, reside, not in pre-existing 
cells of different composition or structure, but simply in different points of a 
pre-existing membrane, which, in the first instance, is homogeneous. The expres- 
sion of Lizzie, that “ the chemical forces in living bodies are subject to the in- 
visible cause by which the forms of organs are produced,” when the action of that 
cause is duly considered, implies, that they are subject to a cause which un- 
doubtedly acts differently at different points of the same matter; but the differ- 
VOL. XVI. PART II. aX 

