PECULIAR STATE OF LIVING MATTER. 329 
combination. This different manner of combination gives 
rise to certain physical peculiarities, especially in density of 
substance, which at first sight seems to constitute a deep 
chasm between the two groups of bodies. Inorganic or 
inanimate natural bodies, such as crystals and the amorphous 
rocks, are in a state of density which we call the firm or 
solid state, and which we oppose to the liquid state of water 
and to the gaseous state of air. It is familiar to every one 
that these three different degrees of density, or states of 
ageregation of anorgana, are by no means peculiar to the 
different elements, but are the results of a certain degree 
of temperature. Every inorganic solid body, by increase of 
temperature, can be reduced to the liquid or melted state, 
and, by further heat, to the gaseous or elastic state. In the 
same way most gaseous bodies, by a proper decrease of 
temperature can first be converted into a liquid state, and 
further, into a solid state of density. 
In opposition to these three states of density of anorgana, 
the living body of all organisms—animals as well as plants 
—is in an altogether peculiar fourth state of aggregation. 
It is neither solid like stone, nor liquid like water, but pre- 
sents rather a medium between these two states, which may 
therefore be designated as the firm-fluid or swollen state of 
aggregation (viscid). In all living bodies, without exception, 
there is a certain quantity of water combined in a peculiar 
way with solid matter, and owing to this characteristic 
combination of water with solid matter we have that 
soft state of aggregation, neither solid nor liquid, which 
is of great importance in the mechanical explanation of 
the phenomena of life. Its cause lies essentially in the 
physical and chemical properties of a simple, indivisible, 
