524 The American Naturalist. [June, 
The present state of our planet is this: First, an ocean of 
atmosphere resting on the surface of the globe, in which exist 
myriads of living things, composed largely of carbon and hydro- 
gen,—both elements that combine with oxygen, evolving an 
immense number of heat-units These elements, carbon and 
hydrogen, while combining together, do so in such a manner that 
the combinations are easily broken up in presence of the oxygen, 
for which they have a stronger affinity. “Oxygen is absorbed 
and carbonic acid evolved in germination, at the birth of the 
young plant, and in flowering when it arrives at an adult state. 
In both instances starch is oxidized and converted, first into 
dextrine, and then into sugar for the nutriment of the young 
embryo, stamens, and pistils, and these processes are accompanied 
by a development of heat. 
“The respiration of the cotyledonary leaves of the embryo, 
and of the corrolline envelope of the stamens and pistils, is, in 
every respect, a true oxidation or combustion of the store of 
saccharine matter, accompanied by the evolution of carbonic acid. 
“ Respiration is absolutely essential to the growth of plants, as 
well as animals.”° It is true that the leaves of plants under 
the influence of sunlight decompose the carbonic acid which 
results from the vital processes, and unite with the carbon 
in the air; a process not found in the animal economy : but it is 
nevertheless true that combustion of carbon to carbonic acid and 
hydrogen to water by the union of these two elements with the 
oxygen of the air proceeds equally with plant and animal, and is 
the source of that heat which constitute their vital force. 
Thus far it has been indicated that the plant and animal are 
such structures as are adapted to exist on a soil of silica, alumina, 
lime, the alkalies, iron, and a few other materials, bathed in an 
atmosphere of oxygen (diluted with nitrogen), at temperatures 
between — 50° and 120° Fahrenheit, and exposed to the rays of 
the sun. 
“The protoplasm which is the real body of the plant cell, to 
which the most important incidents of its life are attached, is a 
sticky, colorless, transparent mass, always containing water, and 
ë Harland Coultas: “ ant, an Illustration of the Organic Life of the Animal.” 
