12 Life and Immortality. 
which, like sugar, starch and cellulose, are made up of the 
three elements, carbon, hydrogen and oxygen, but are, com- 
paratively speaking, poorly supplied with quaternary 
compounds, or those which contain an additional element of 
nitrogen. Animals, on the contrary, are rich in quaternary 
nitrogenized compounds, such as albumen or fibrin. Still, 
in both kingdoms we find nitrogenized and non-nitrogen- 
ized compounds, and it is only in the proportion which these 
sustain to each other in the organism that animals differ in 
any way from plants. 
Before the invention of the microscope, no independent 
voluntary movements, if we except the opening and closure 
of flowers, and their turning towards the sun, the drooping 
of the leaves of sensitive plants under irritation, and some 
other kindred phenomena, were known in plants. Now, how- 
ever, we know of many plants which are endowed, either 
when young or throughout life, with the power of effecting 
voluntary movements apparently as spontaneous and inde- 
sendent as those performed by the lower animals, the move- 
ments being brought about by means of little vibrating cilia, 
or hairs, with which a part or the whole of the surface is 
furnished. When it is added that many animals are perma- 
nently rooted, in their fully-grown condition, to solid objects, 
it will at once be apparent that no absolute distinction can 
be made between animals and plants merely because of the 
presence or absence of independent locomotive power. 
There is, however, a test, the most reliable of all that have 
been discovered, by which an animal may be distinguished 
from a plant, and that is the nature of the food and the prod- 
ucts which are elaborated therefrom in the body. Plants 
live upon such inorganic substances as water, carbonic acid 
and ammonia, and they have the power of manufacturing 
out of these true organic materials, and are. therefore the 
great producers of nature. All plants which contain green 
coloring matter, technically called chlorophyll, break up 
carbonic acid in the process of digestion into its two 
