hat of ecphoria of the cerebral engrams
of the ancestors, accumulated in the hereditary mneme.

=Heredity of Acquired Characters.=--While _Darwin_ and _Haeckel_
affirmed the possibility of the heredity of characters acquired during
life by different tissues, for instance the brain, _Weismann_ limits
the possibility to everything that can modify the nucleoplasm of the
germinal cells. We must first eliminate the question of the phenomena
of blastophthoria, which we shall consider next, and which _Weismann_
was, I think, the first to comprehend, without giving them the name.

On one hand we see the singular effects of castration, which we have
already considered; on the other hand, an extraordinary constancy in
the hereditary characters of the species. For more than three thousand
six hundred years, which corresponds to about eight hundred
generations, the Jews have been circumcised. Nevertheless, if a Jew
ceases to circumcise his offspring the prepuce of his children grows
as it did three thousand six hundred years ago, although, during the
eight hundred generations in question, its absence from birth has
prevented it reacting on the germinal cells of the individuals. If the
engraphia of the external world could sensibly modify in a few
generations the hereditary mneme of the species, it appears evident
that the Jewish infants of the present day would be born without
prepuce, or at least with an atrophied one.

It is on such facts, which are innumerable in natural history, that
_Weismann_ relies to repudiate absolutely the heredity of characters
acquired by non-germinal organs and to attribute the development of
organisms to blends and combinations due to conjugation, or crossing,
as well as to natural selection, which he regards as all-powerful.
_Darwin_ well recognized the difficulty in question, and being unable
to explain the facts, had recourse to the hypothesis of _pangenesis_,
that is of small particles detached from all parts of the body and
transported by the blood to the germinal cells, to transmit to them,
for example, the qualities acquired by the brain during life. This
hypothesis was so improbable that _Darwin_ himself was forced to
recognize it. Let us examine the facts.

On the one hand a newly born Chinese transported and brought up in
France will learn French, and will show no inclination to learn or
understand Chinese. This well-established fact seems in favor of
_Weismann_ and against the heredity