28G 



DEFINITE ACTION OF THE 



Chap. XXIII. 



O' 







importance than the conditions to which it has been exposed. It seems 

 indeed, to be a general rule that conspicuous variations occur rarely' 

 and in one individual alone out of many thousands, though all may 

 have been exposed, as far as we can judge, to nearly the same conditions. 

 As the most strongly marked variations graduate insensibly into the most 

 trifling, we are led by the same train of thought to attribute each slight 

 variation much more to innate differences of constitution, however caused 

 than to the definite action of the surrounding conditions. 



We are led to the same conclusion by considering the cases, former! v 

 alluded to, of fowls and pigeons, which have varied and will no doubt 

 on varying in directly opposite ways, though kept during many genera- 

 tions under nearly the same conditions. Some, for instance, are born with 

 their beaks, wings, tails, legs, &c, a little longer, and others with these 

 same parts a little shorter. By the long-continued selection of such 

 slight individual differences, which occur in birds kept in the same aviary, 

 widely different races could certainly be formed; and long-continued 

 selection, important as is the result, does nothing but preserve the variations 

 which appear to us to arise spontaneously. 



In these cases we see that domesticated animals vary in an indefinite 

 number of particulars, though treated as uniformly as is possible. On the 

 other hand, there are instances of animals and plants, which, though exposed 

 to very different conditions, both under nature and domestication, have 

 varied in nearly the same manner. Mr. Layard informs me that he has 

 observed amongst the Caffres of South Africa a clog singularly like an 

 arctic Esquimaux dog. Pigeons in India present nearly the same wide 

 diversities of colour as in Europe ; and I have seen chequered and simply 

 barred pigeons, and pigeons with blue and white loins, from Sierra Leone, 

 Madeira, England, and India. New varieties of flowers are continually 

 raised in different parts of Great Britain, but many of these are found by 

 the judges at our exhibitions to be almost identical with old varieties. A 

 vast number of new fruit-trees and culinary vegetables have been pro- 

 duced in North America : these differ from European varieties in the 

 same general manner as the several varieties raised in Europe differ from 

 each other ; and no one has ever pretended that the climate of America 

 has given to the many American varieties any general character by which 

 they can be recognised. Nevertheless, from the facts previously advanced 

 on the authority of Mr. Meehan with respect to American and European 

 forest-trees, it would be rash to affirm that varieties raised in the two 

 countries would not in the course of ages assume a distinctive character. 



Mr. Masters hn.S TPPOrflpfl n. striVi-ncr -ffiYvf-56 "kooTM-ncr rm f!-na cn^WI. ' hfi 



raised numerous plants of HyUscus Syriacus from seed collected in South 

 Carolina and the Holy Land, where the parent-plants must have been 

 exposed to considerably different conditions ; yet the seedlings from both 

 localities broke into two similar strains, one with obtuse leaves and purple 

 or crimson flowers, and the other with elongated leaves and more or less 

 pink flowers. 



56 ' Gardener's Chronicle,' 1S57, p. G20. 



