Chap. XXII. CAUSES OF VARIABILITY. 241 



by thj conditions of life to which each being, and more 

 especially its ancestors, have been exposed. 



No one doubts that domesticated productions are more 

 variable than organic beings which have never been removed 

 from their natural conditions. Monstrosities graduate so in- 

 sensibly into mere variations that it is impossible to separate 

 them; and all those who have studied monstrosities believe 

 that they are far commoner with domesticated than with wild 

 animals and plants ; 3 and in the case of plants, monstrosities 

 would be equally noticeable in the natural as in the cultivated 

 state. Under nature, the individuals of the same species are 

 exposed to nearly uniform conditions, for they are rigorously 

 kept to their proper places by a host of competing animals and 

 plants ; they have, also, long been habituated to their condi- 

 tions of life ; but it cannot be said that they are subject to 

 quite uniform conditions, and they are liable to a certain 

 amount of variation. The circumstances under which our 

 domestic productions are reared are widely different : they 

 are protected from competition ; they have not only been 

 removed from their natural conditions and often from their 

 native land, but they are frequently carried from district to 

 district, where they are treated differently, so that they rarely 

 remain during any considerable length of time exposed to 

 closely similar conditions. In conformity with this, all our 

 domesticated productions, with the rarest exceptions, vary far 

 mors than natural species. The hive-bee, which feeds itself and 

 follows in most respects its natural habits of life, is the least 

 variable of all domesticated animals, and probably the goose 

 is the next least variable; but even the goose varies more 

 than almost any wild bird, so that it cannot be affiliated with 

 perfect certainty to any natural species. Hardly a single 

 plant can be named, which has long been cultivated and 

 propagated by seed, that is not highly variable ; common rye 

 (Secale cereale) has afforded fewer and less marked varieties 

 than almost any other cultivated plant ; 4 but it may be 



3 Isid. Geoffroy St.-Hilaiie, 'Hist. 1841, p. 115. 

 des Anomalies,' tom. iii. p. 352; Mo- 4 Metzger, 'Die Getrei learten. 



tjum-Tandon, 'Teratologic VYgetale,' 1841, s. 39. 



