Seite - 28 - in The Origin of Species

28 ORIGIN OF SPECIES but to show how singular the laws are which determine thei reproduction of animals under confinement, I may mention that carnivorous animals, even from the tropics, breed in this country pretty freely under confinement, with the excep- tion of the plantigrades or bear family, which seldom pro- duce young; whereas carnivorous birds, with the rarest ex- ceptions, hardly ever lay fertile eggs. Many exotic plants have pollen utterly worthless, in the same condition as in the most sterile hybrids. When, on the one hand, we see domes- ticated animals and plants, though often weak and sickly, breeding freely tmder confinement; and when, on the other hand, we see individuals, though taken young from a state of nature perfectly tamed, long-lived and healthy (of which I could give numerous instances), yet, having their repro- ductive system so seriously affected by unperceived causes as to fail to act, we need not be surprised at this system, when it does act under confinement, acting irregularly, and pro- ducing offspring somewhat unlike their parents. I may add, that as some organisms breed freely under the most unnat- ural conditions (for instance, rabbits and ferrets kept in hutches), showing that their reproductive organs are not easily affected ; so will some animals and plants withstand domestication or cultivation, and vary very slightly—per- haps hardly more than in a state of nature. Some naturalists have maintained that all variations are connected with the act of sexual reproduction; but this is certainly an error; for I have given in another work a long list of "sporting plants," as they are called by gardeners;— that is, of plants which have suddenly produced a single bud with a new and sometimes widely different character from that of the other buds on the same plant. These bud-varia- tions, as they may be named, can be propagated by grafts, offsets, etc., and sometimes by seed. They occur rarely under nature, but are far from rare under culture. As a single bud out of the many thousands, produced year after year on the same tree under uniform conditions, has been known suddenly to assume a new character ; and as buds on distinct trees, growing under different conditions, have some- times yielded nearly the same variety—for instance, buds on peach-trees producing nectarines, and buds on common roses