Chap. XXII. CAUSES OF VARIABILITY. 253 



Gartner declares,^^ and his experience is of the highest rahie on 

 Biich a point, that, when he crossed native plants wliich had not 

 been cultivated, he never once saw in the offspring any new character ; 

 but that from the odd manner in which the characters derived from 

 the parents were combined, they sometimes appeared as if new. 

 ^Yhen, on the other hand, he crossed cultivated plants, he admits 

 that new characters occasionally appeared, but he is strongly 

 inclined to attribute their appearance to ordinary variability, not 

 in any M'ay to the cross. An opposite conclusion, however, apj)ears 

 to me the more probable. According to Kulreuter, hybrids in the 

 genus Mirabilis vary almost infinitely, and he describes new and 

 singular characters in the form of the seeds, in the colour of the 

 anthers, in the cotyledons being of immense size, in new and highly 

 peculiar odours, in the flowers expanding early in the season, and 

 in their closing at night. With respect to one lot of these hybrids, 

 he remarks that they presented characters exactly the reverse of 

 what might have been expected from their parentage.^^ 



Prof. Lecoq"^ speaks strongly to the same effect in regard to this 

 same genus, and asserts that many of the hybrids from Mirabilis 

 jalapa and multifiora might easily be mistaken for distinct species, 

 and adds that they differed in a greater degree than the other 

 species of the genus, from M. jalapa. Herbert, also, has describeu^'^ 

 certain hybrid Ehododendions as being '' as unlike all others in 

 " foliage, as if they had been a separate species." The common 

 experience of floriculturists proves that the crossing and recrossing 

 of distinct but allied plants, such as the species of Petunia, Calceo- 

 laria, Fuchsia, Verbena, &c., induces excessive variability; hence 

 the appearance of quite new characters is probable. M. Carriere^" 

 has lately discussed this subject : he states that Erythrina cristaf/tilli 

 had been multiplied by seed for many years, but hcid not yielded 

 any varieties : it was then crossed with the allied A', herbacea, and 

 " the resistance was now overcome, and varieties were produced 

 " with flowers of extremely different size, form, and colour." 



From the general and apparently well-founded belief that the 

 crossing of distiiKit species, besides commingling their characters, 

 adds greatly to their variability, it has probably arisen that some 

 botanists have gone so far as to maintain ^^ that, when a genus 

 includes only a single species, this when cultivated never varies. 

 The proposition made so broadly cannot be admitted; but it is 

 probably true that the variability of monotypic genera when culti- 



3* ' Bastarderzeugung,* s. 249, 255, ^* Abstracted in ' Gard. Chronicle,' 



295. 1860, p. 1081. 



^^ 'Nova Acta, St. Petersburg,' 39 This was the opinion of the elder 



1794, p. 378 ; 1795, pp. o07, 31:3, De Candolle, as quoted in ' Die. Class. 



316 ; 1787, p. 407. d'Hist. Nat.,' torn. viii. p. 405. Puvis, 



^^ *De la Fe'condation,' 18G2, p. in his work, ' De la Degeneration,* 



311. 1837, p. 37, hua discussed thjs sam<* 



" * Amaryllidaceae,' 1837, p. 362. point. 



33 



