new strength since the introduction of the Darwinian theory of the
evolution of species. Along with the latest discoveries in
physiology, biology, embryology and other branches of modern science,
the popular simple meaning of heredity--that the offspring not only
resemble their parents among animals as well as among men, but inherit
all the individual peculiarities, life and character of their
parents--has taken the shape of the most complicated and difficult
problem which it is almost impossible to solve. Our minds are no
longer satisfied with Haeckel's definition that heredity is simply an
overgrowth of the individual, a simple continuity of growth; but we
want to know the particular method by which hereditary transmission
takes place. We ask, how can a single cell reproduce the whole body
of the offspring, its mind, character and all the peculiarities of an
organism? Out of the myriads of cells of which a body is composed,
what kind of cell is that which possesses the power of reproducing the
peculiarities, both mental and physical, which are to be found in the
form of the new-born babe? This is the most puzzling of all the
problems which the scientific mind has ever encountered. The
fundamental question connected with the theory of heredity is: How can
a single cell of the body contain within itself all the hereditary
tendencies of the hypothesis of the continuity of the germ-plasm gives
an identical starting-point to each successive generation, and thus
explains how it is that an identical product arises from all of
them. In other words, the hypothesis explains heredity as part of the
underlying problems of assimilation and of the causes which act
directly during ontogeny. (Vol. I, p. 170.)

According to Weismann, all the peculiarities which we find in an
organism are not inherited by the organism from that of the parents,
but he says: "Nothing can arise in an organism unless the