SEXUAL AND NON-SEXUAL HEREDITY. 20I 



mind has ever raised about man's existence. And, we add, 

 these most important questions are solved, by means of the 

 Theory of Descent, in a purely mechanical and purely 

 monistic sense ! 



There can then be no further doubt that, in the sexual 

 propagation of man and all higher organisms, inheritance, 

 which is a purely mechanical process, is directly dependent 

 upon the material continuity of the producing and pro- 

 duced organism, just as is the case in the simplest non- 

 sexual propagation of the lower organisms. However, I 

 must at once take this opportunity of drawing atten- 

 tion to an important difference which inheritance presents 

 in sexual and non-sexual propagation. It is a fact long 

 since acknowledged, that the individual peculiarities of the 

 producing organism are much more accurately transmitted 

 to the produced organism by non-sexual than by sexual 

 propagation. Gardeners have for a long time made use of 

 this fact in many ways. When, for instance, a single 

 individual of a species of tree with stiff, upright branches 

 accidentally produces down-hanging branches, a gardener, 

 as a rule, cannot transmit this peculiarity by sexual, but 

 only by non-sexual propagation. The twigs cut off such a 

 weeping tree and planted as cuttings or slips, afterwards 

 produce trees having likewise hanging branches, as, for 

 example, the weeping willows and beeches. Seedlings, on 

 the other hand, which have been reared out of the seed of 

 such a weeping tree, generally have the original stiff and 

 upright form of branches possessed by their ancestors. 

 The same may be observed in a very striking manner in 

 the so-called " copper-coloured trees," that is, varieties of 

 trees which are characterized by a red or reddish brown 



