CHAP. I.j VARIATION UNDER DOMESTICATION. 7 



the conditions, and partly from the similarity, as Kolreuter and 

 others have remarked, between the variability which follows from 

 the crossing of distinct species, and that which may be observed 

 with plants and animals when reared under new or unnatural con- 

 ditions. Many facts clearly show how eminently susceptible the 

 reproductive system is to very slight changes in the surrounding 

 conditions. Nothing is more easy than to tame an animal, and few 

 things more difficult than to get it to breed freely under confine- 

 ment, even when the male and female unite. How many animals 

 there are which will not breed, though kept in an almost free state in 

 their native country ! This is generally, but erroneously, attributed 

 to vitiated instincts. Many cultivated plants display the utmost 

 vigour, and yet rarely or never seed ! In some few cases it has 

 been discovered that a very trifling change, such as a little more 

 or less water at some particular period of growth, will determine 

 whether or not a plant will produce seeds. I cannot here give the 

 details which I have collected and elsewhere published on this 

 curious subject ; but to show how singular the laws are which 

 determine the 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 exception 

 of the plantigrades or bear family, which seldom produce young ; 

 whereas carnivorous birds, with the rarest exceptions, 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 domesticated animals and plants, though often 

 weak and sickly, breeding freely under confinement ; and when, 

 on the other hand, we see individuals, though taken young from . 

 state of nature perfectly tamed, long-lived and healthy (of which 

 I could give numerous instances), yet having their reproductive 

 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 producing offspring somewhat 

 unlike their parents. I may add, that as some organisms breed 

 freely under the most unnatural 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 

 perhaps hardly more than in a state of nature. 



Some naturalists have maintained that all variations are con- 

 nected 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-variations, as they may be named, can be pro- 



