"Between individuals of the same species, some of which are constantly well nourished, and in circumstances favorable to their entire development, while the others live under reversed circumstances, there is brought about a difference in the condition of these individuals which gradually becomes very remarkable. How many examples could I not cite regarding animals and plants, which would confirm the grounds for this view! Now, if the circumstances remain the same, rendering habitual and constant the condition of individuals badly fed, diseased, or languishing, their internal organization becomes finally modified, and reproduction between the individuals in question preserves the acquired modifications, and ends in giving rise to a race very distinct from that of the individuals which unceasingly meet with circumstances favorable to their development. "A very dry spring-time is the cause of the grass of a field growing very slowly, remaining scraggy and puny, flowering and fruiting without growing much. "A spring interspersed with warm days and rainy days makes the same grass grow rapidly, and the harvest of hay is then excellent. "But if any cause perpetuates the unfavorable circumstances surrounding these plants, they vary proportionally, at first in their appearance and general condition, and finally in several particulars of their characters. "For example, if some seed of any of the grasses referred to should be carried into an elevated place, on a dry and stony greensward much exposed to the winds, and should germinate there, the plant which should be able to live in this place would always be badly nourished, and the individuals reproduced there continuing to exist under these depressing circumstances, there would result a race truly different from that living in the field, though originating from it. The individuals of this new race would be small, scraggy, and some of their organs, having developed more than others, would then offer special proportions. "Those who have observed much, and who have consulted the great collections, have become convinced that in proportion as the circumstances of habitat, exposure, climate, food, mode of life, etc., come to change, the characters of size, form, proportion between the parts, color, consistence, agility, and industry in the animals change proportionally. "What nature accomplishes after a long time, we bring about every day by suddenly changing, in the case of a living plant, the circumstances under which it and all the individuals of its species exist.