MENDELISM 175 
clear and definite information only when applied to 
cases where clearly definable characters have distin- 
guished the parental forms examined. This, however, 
is in great part due to the fact that the experimental 
method has scarcely yet been used in dealing with 
characters of a less definite nature. The science is 
still in its infancy, and attention has naturally been 
first paid to the simpler problems which it affords. 
The difficulties of treatment which confront those who 
would deal with highly variable characters and those 
of a ‘more or less’ nature are considerable, although 
there is no reason for supposing that such problems are 
insuperable. As we have seen, however, the majority 
of characters which distinguish species or races from 
one another appear to be of a perfectly definite descrip- 
tion, so that the limitation just referred to is not so 
serious as might appear at first sight. The recent 
revival of work upon the subject of inheritance by 
the use of breeding methods has, as a matter of fact, 
already been rewarded. with results as valuable and 
as clear as could possibly have been anticipated— 
results which are sufficient in themselves to show that 
the discovery made by Mendel was of an importance 
little inferior to those of a Newton or a Dalton. 
It is important to remember that every animal or 
plant, which has come into existence in the ordinary 
way through sexual generation, owes its individuality 
to the mingled natures of two separate parents. The 
following lines, in which the poet Goethe speaks of 
his own hereditary endowment, have been quoted 
more than once in this connection ; 
