![]() ![]() ![]() Unintentionally he exposes organic beings to new and changing conditions of life, and variability ensues but similar changes of conditions might and do occur under nature. But the variability, which we almost universally meet with in our domestic productions, is not directly produced, as Hooker and Asa Gray have well remarked, by man he can neither originate varieties, nor prevent their occurrence he can preserve and accumulate such as do occur. Under domestication, it may be truly said that the whole organisation becomes in some degree plastic. Let the endless number of slight variations and individual differences occurring in our domestic productions, and, in a lesser degree, in those under nature, be borne in mind as well as the strength of the hereditary tendency. ![]() "How will the struggle for existence, briefly discussed in the last chapter, act in regard to variation? Can the principle of selection, which we have seen is so potent in the hands of man, apply under nature? I think we shall see that it can act most efficiently. ![]()
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