26 
Dr. Carpenter alleged this as a distinction—“ Where we find 
oxygen exhaled and carbonic acid given off we have an animal; and 
that where carbonic acid is absorbed and oxygen given out we have 
a plant.” An elaborate series of experiments had, however, been 
lately made by Dr. J. C. Draper, of New York, and the conclusion 
he came to was, that “growth as applied to evolution of structure or 
organisation is inseparably connected with oxidation ;” that was to 
say, that in the process of that cell-development whereby the structure 
of a vegetable organism was increased, carbonic acid was given off 
and oxygen inhaled, precisely the same as in animals. It was onlythe 
green parts that at any time exhaled oxygen, and then only under the 
influence of sunshine. The other parts of the plant above ground, 
which were not green, viz., the stem, twigs, flowers, &c., were at all 
times, day and night, exhaling carbonic acid. The whole history of the 
plant, from the time the seed was planted till its death, was a continual . 
story of oxidation. Two distinct operations connected with the 
respiratory functions of plants must be distinguished. There was the 
preparation of this substance, out of which the cells were- built and 
nourished. It was in this that the carbon was obtained from the 
carbonic acid, and oxygen exhaled. It was in this that the remarkable 
substance, chlorophyl, was intimately concerned. 
The next inquiry was, by what power the functions of the vegetable 
organism were carried on? If they meant by these some special 
property which existed out of the animal or plant they raised up a kind 
of spectre, which was but the magnified image of their own ignorance. 
Forty years ago there was a hard and fast line between the inorganic 
and the organic—they could not build up in their laboratories the 
substances found in animal and vegetable organisms. The force 
which did this, to use Dr. Prant’s words, “could not possibly be 
chemical ; it was vital, and its nature was completely unknown.” But 
now the chemist could prepare at least 1,000 substances precisely 
the same as those now formed within the living plant and animal. 
Not only were organisms affected by light, heat, electricity, and 
magnetism, but plants, when placed under the different colours of the 
Solar Spectrum, were stimulated to the greatest activity under the 
yellow ray, which was the most luminous to the eye. In measuring 
the sum total of the vital energy of plants, scientific inquirers were at 
a great disadvantage ; with man they could estimate the amount of 
