imagine that the passage of some specific organism through the
reproductive cells may take place, as in the case of syphilis. We are,
however, entirely ignorant of the nature of the former disease. This
suggested explanation may not perhaps apply to the other cases; but we
must remember that animals which have been subjected to such severe
operations upon the nervous system have sustained a great shock, and if
they are capable of breeding, it is only probable that they will produce
weak descendants, and such as are easily affected by disease. Such a
result does not, however, explain why the offspring should suffer from
the same disease as that which was artificially induced in the parents.
But this does not appear to have been by any means invariably the case.
Brown-Sequard himself says: 'The changes in the eye of the offspring were
of a very variable nature, and were only occasionally exactly similar to
those observed in the parents.'

"There is no doubt, however, that these experiments demand careful
consideration, but before they can claim scientific recognition, they
must be subjected to rigid criticism as to the precautions taken, the
nature and number of the control experiments, &c.

"Up to the present time such necessary conditions have not been
sufficiently observed. The recent experiments themselves are only
described in short preliminary notices, which, as regards their accuracy,
the possibility of mistake, the precautions taken, and the exact
succession of individuals affected, afford no data on which a scientific
opinion can be founded" (pp. 81, 82).

The line Professor Weismann takes, therefore, is to discredit the facts;
yet on a later page we find that the experiments have since been repeated
by Obersteiner, "who has described them in a very exact and unprejudiced
manner," and that "the fact"--(I imagine that Professor Weismann intends
"the facts")--"cannot be doubted."

On a still later page, however, we read:--

"If, for instance, it could be shown that artificial mutilation
spontaneously reappears in the offspring with sufficient frequency to
exclude all possibilities of chance, then such proof [_i.e._, that
acquired characters can be transmitted] would be forthcoming. The
transmission of mutilations has been frequently asserted, and has been
even recently again brought forward, but all the supposed instances have
broken down when carefully examined" (p. 390).

Here, then, we are told that