1866. | On Cell Life. 241 
are brought to greater perfection, and the performances of the entire 
organism become more varied and numerous. 
The best type of such an association of organic individuals is a 
lant. Here we see different groups of cells execute different offices 
which benefit the whole plant. One set extracts material from the 
ground, another elaborates it im various ways; others again draw 
material from the air; others are especially fruitful in producing new 
generations. But we do not attain to the higher efforts of physical 
activity in the plant. The reason of this is easily seen. 
Tn plants, each single cell surrounds itself directly with a mem- 
brane of the so-called cellulose, the substance which we have before 
us in wood, in cotton, and in paper. The cells are, by means of 
this, individually shut up; they can, it is true, influence one another 
to a certain degree, in that they can transmit material ‘to one 
another; but they cannot infiuence one another to an unlimited 
extent; they cannot share their conditions, their sensations, we 
may even say their experiences, with one another. Each therefore 
is confined to the bare circle of its own sensations (which we are as 
little able to dispute in plant-cells as in animal-cells), and therefore 
it can reach to no higher grade of psychical life. 
The cells of a plant are, in a word, like a number of men shut 
up from childhood together in a cellular prison, who perhaps might 
have exercised much important influence on one another, but 
between whom all spiritual intercourse has been prevented. These 
men would never display the deeper characteristics of spiritual 
development. 
In the higher animals there are numerous groups of cells which 
are disposed in a manner analogous to that observed in the plant 
cells; that is to say, they le isolated, yet near each other, though 
not enclosed in the same hard dwellings as in plants. Such agegre- 
gates of cells, for example, are the blood and the epithelium. The 
epithelium is the name given to the layers of cells which lie 
arranged like strata wherever an organic structure is bounded towards 
external space, as in the outer skin (epidermis), and the slime-skin 
or mucous membrane which lines the surface of internal cavities 
open to external space. Many other tissues also form the same 
kind of cell-masses, upon the principle of the plant’s organization. 
Their action has been long designated as ‘ vegetative,’ correctly 
referring to the analogies which they present to plant-life. 
In the higher animals a new system of cells is added to this 
vegetative group, which are disposed on a totally different plan. 
Tt defines what is truly animal, and its actions are rightly desig- 
nated ‘ animal.’ 
' In fact, the difference between plants and animals does not 
really lie in their elementary components. Both kingdoms are, 
as we saw, aud as most observers in both now admit, constructed 
