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 



