"The plant, unlike the animal, has provided a special mechanism—a unique laboratory—through which it is able to manufacture from the crude salts in watery solution, with the aid of another element taken from the air, a new compound which will serve the protoplasmic cell with food. That is to say, the plant organism as a whole comprises a laboratory for compounding the crude elements, which by themselves cannot be used as nourishment, into a substance that can be used as nourishment. ...The plant is the only place in the world where foodstuffs are manufactured, and that no animal of any kind could live without nourishment that was originally manufactured by some plant, the vital importance of the matter will be manifest."