Chap. XIII. EEVERSION. 11 



by segments. Yilmorin 21 lias also recorded several cases with 

 plants derived from seed, of flowers reverting by stripes or 

 blotches to their primitive colours : he states that in all such 

 cases a white or pale-coloured variety must first be formed, 

 and, when this is propagated for a length of time by seed, 

 striped seedlings occasional^ make their appearance ; and 

 these can afterwards by care be multiplied by seed. 



The stripes and segments just referred to are not due, as far 

 as is known, to reversion to characters derived from a cross, 

 but to characters lost by variation. These cases, however, as 

 Naudin 22 insists in his discussion on disjunction of character, 

 are closely analogous with those given in the eleventh chapter, 

 in which crossed plants have been known to produce half- 

 and-half or striped flowers and fruit, or distinct kinds of 

 flowers on the same root resembling the two parent-forms. 

 Many piebald animals probably come under this same head. 

 Such cases, as we shall see in the chapter on Crossing, appa- 

 rently result from certain characters not readily blending 

 together, and, as a consequence of this incapacity for fusion, 

 the offspring either perfectly resemble one of their two 

 parents, or resemble one parent in one part, and the other 

 parent in another part ; or whilst young are intermediate in 

 character, but with advancing age revert wholly or by seg- 

 ments to either parent-form, or to both. Thus, young trees 

 of the Gytisus adami are intermediate in foliage and flowers 

 between the two parent-forms ; but when older the buds 

 continually revert either partially or wholly to both forms. 

 The cases given in the eleventh chapter on the changes which 

 occurred during growth in crossed plants of Tropaeolum, Cereus, 

 Datura, and Lathyrus are all analogous. As, however, these 

 plants are hybrids of the first generation, and as their buds 

 after a time come to resemble their parents and not their 

 grandparents, these cases do not at first appear to come under 

 the law of reversion in the ordinary sense of the word ; never- 

 theless, as the change is effected through a succession of bud- 

 generations on the same plant, they may be thus included. 



Analogous facts have been observed in the animal kingdom, 



21 Verlot, ' Des Variete's,' 1865, torn. i. p. 25. Alex. Braun (in his ' Re- 

 p. 63. juvenescence,' RaySoc, 1853, p. 315) 



22 'Nouvelles Archives du Museum,' apparently holds a similar opinion. 



