SEXUAL AND NON-SEXUAL HEREDITY. 201 
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 
