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254 CAUSES OF VARIABILITY. Chap. XXII. 



natural conditions. Monstrosities graduate so insensibly 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 notice- 

 able 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 conditions 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 cir- 

 cumstances 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 never remain during a considerable length of 

 time exposed to closely similar conditions. In conformity with 

 this, all our domesticated productions, with the rarest excep- 

 tions, vary far more 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 pro- 

 bably 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 doubted 

 whether the variations of this, the least valuable of all our 

 cereals, have been closely observed. 



Bud-variation, which was fully discussed in a former chapter, 

 shows us that variability may be quite independent of seminal 

 reproduction, and likewise of reversion to long-lost ancestral 

 characters. No one will maintain that the sudden appearance 



3 Isid. Geoffroy St. Hilaire, ' Hist, des Anomalies,' torn. iii. p. 352 ; Moquin- 

 Tandon, ' Teratologie Vegetale,' 1841, p. 115. 



4 Metzger, 'Die Getreidearten,' 1841, s. 39. 



