10 



INHERITANCE. 



Chap. XII [. 



Naiidin.^^ The tendency dififers in degree or strength in 

 different groups, and partly depends, as we shall presently 

 see, on whether the parent-plants have been long cultivated. 

 Although the tendency to reversion is extremely general 

 with nearly all mongrels and hybrids, it cannot be considered 

 as invariably characteristic of them ; it may also be mastered 

 by long-continued selection ; but these subjects will more 

 properly be discussed in a future chapter on Crossing. From 

 what we see of the power and scope of reversion, both in pure 

 races, and when varieties or species are crossed, we may infer 

 that characters of almost every kind are capable of reappear- 

 ing after having been lost for a great length of time. But it 

 does not follow from this that in each particular case certain 

 characters will reappear ; for instance, this will not occur 

 when a race is crossed with another endowed with prepotency 

 of transmission. Sometimes the power of reversion wholly 

 fails, without our being able to assign any cause for the 

 failure : thus it has been stated that in a French family in 

 which 85 out of above 600 members, during six generations, 

 had been subject to night-blindness, " there has not been a 

 single example of this affection in the children of parents who 

 were themselves free from it."'-° 



Heversion through Bud-propagation — Partial Iteversio7i, hy seg- 

 ments in the same floicer or fruit, or in different parts of the body 

 in the same individual animal. — In the eleventh chapter many 

 cases of reversion by buds, independently of seminal genera- 

 tion, were given — as when a leaf-bud on a variegated, a 

 curled, or laciniated variety suddenly reassumes its proper 

 character ; or as when a Provence-rose appears on a moss-rose, 

 or a peach on a nectarine-tree. In some of these cases only 

 half the flower or fruit, or a smaller segment, or mere stripes, 

 reassume their former character ; and here we have reversion 



^^ Kolreuter gives curious cases in 

 his ' Dritte Fortsetzung,' 1766, ss. 53, 

 59; and in his well-known 'Memoirs 

 on Lavatera and Jalapa.' Gartner, 

 * Bastarderzevigung,' ss. 437, 441, &c. 

 Naudin, in his " Recherches sur 

 I'Hybridite," ' Nouvelles Archives du 

 Museum,' tom. i. p. 25. 



^'^ Quoted by Mr. Sedgwick in 



' Med.-Chirurg. Review,' April, 1861, 

 p. 485. Dr. H. Dobell, in 'Med.- 

 Chirurg. Transactions,' vol. xlvi., 

 gives an analogous case, in which, in 

 a large family, fingers with thickened 

 joints were transmitted to several 

 members during five generations ; 

 but when the blemish once disappeared 

 it never reappeared. 



