REJUVENESCENCE IN NATURE. 313 



atropiirpurea), colour and doubling of the flower (Tulipa, 

 Dianthus, Primula, Dahlia, &c.) ; as also, finally, the 

 numerous varieties, chiefly marked by the condition of 

 the fruit, which we have among our cultivated orchard 

 and other fruits. The origin of the varieties mentioned 

 here does not depend so much upon an alteration 

 gradually insinuating itself into the external conditions 

 of existence, as upon a development, under favorable 

 conditions, of the multiformity possible within the limits, 

 of a certain type, which is implied especially in the fact 

 that very different varieties may arise from one and the 

 same sowing, even from the seeds of one and the same 

 fruit, and this without influence of impregnation from a 

 foreign source, and under equal external circumstances.* 

 The development of this multiplicity takes place ordinarily, 

 as stated, by means of reproduction, and it may disap- 

 pear in the same process ; the new varieties grow up from 

 seed, and may in like manner return to the parent-form 

 by sowing. But sometimes a similar production and a 

 similar retrogression of the variety takes place by means 



forest near Sondershausen, in Thuringia; it is propagated by cuttings, 

 since when sown it mostly returns to the common green beech. See 

 Bechstein, ' Forstbot.,' f. 1, p. 229. Ibid., (267,) mention is made of a 

 copper oak, (Quercus pedunculata sanguinea,) of which a single tree is said 

 to exist in the Lauchner Forest, near Gotha. 



* According to Van Mons, this sometimes goes so far that a peculiar 

 variety springs from each single seed, e. #., from the ten seeds of a pear, 

 were developed an equal number of new sorts of pear. Cultivation of course 

 has an influence upon the production of new varieties, yet not on the indi- 

 viduals directly exposed to its effects, but on their progeny. In most cases it 

 is impossible to demonstrate a definite relation of the influence of cultivation 

 upon the qualities of the varieties thence arising; it appears rather, on the 

 whole, as if the unusual conditions, favorable to a luxuriant state of develop- 

 ment, afforded by cultivation, awakened in the plant the inward impulse to 

 the display of all those variations possible within the more or less narrowly 

 circumscribed limits of the species. According to the experience of gar- 

 deners, in particular of the celebrated Belgian orchard-fruit grower. Van 

 Mons, this impulse is only gradually awakened in the wild plant subjected 

 to cultivation, often requiring several generations, until it has attained ils 

 maximum and is finally extinguished in the formation of constant varieties. 

 At the same time, the fact of experience is remarkable, that improved 

 varieties propagated by cuttings acquire so much the more inclination to 

 return to the parent form the longer they are propagated in this way. (See 

 Godron, ' De 1'Espece et des Races,' p. 83, where also are enumerated the 

 treatises of Van Mons not within my reach here.)' 



