oduced differences in the species of plants and
animals greater than occur among those which are universally
recognised as belonging to different species. Therefore it was, up to
a certain point, proved that species can change and furthermore there
was established the possibility of a common ancestry for organisms
which partake of the characteristics of different species.

Darwin now examined the question whether there were not in nature
causes--which without the conscious intention of the breeder--might in
the course of time, by means of heredity, produce changes in the
living animal analogous to those produced by scientific breeding.
These causes he found in the disproportion between the enormous number
of germs made by nature and the small number of beings which actually
come to maturity. But as the germ struggles for its own development
there is of necessity a consequent struggle for existence, which not
only shows itself directly in the wear and tear of the body, but also
as a struggle for space and light, as in the case of plants. And it is
evident that in this fight those individuals have the best prospect of
coming to maturity and reproducing themselves which possess certain
qualities, perhaps insignificant, but advantageous in their fight for
existence. There is a tendency towards the inheritance of these
individual properties, and if they occur in several individuals of the
same species towards development in the direction once taken, by
virtue of the accumulated heredity, while the individuals which are
not possessed of these qualities succumb more easily and little by
little disappear in the struggle for existence. Thus a species
naturally changes by the survival of the fittest.

Against this theory of Darwin Herr Duehring urges that the origin of
the idea of the struggle for existence is, as Darwin himself
confessed, based on the views of the political economist and theorist,
Malthus, on the population question, and he covers it with all the
abuse appropriate to the clerical Malthusian views on keeping down the
population. Now it happens that Darwin never said that the cause of
the struggle for existence theory was to be sought from Malthus. He
only said that his theories respecting the struggle for existence are
the theories of Malthus applied to the entire vegetable and animal
world. How great a blunder Darwin made when he so naively accepted the
teachings of Malthus without examination may be seen from