d shown to be not
conclusive. The mutilation itself--a section of certain nerves--was
never inherited, but the resulting epilepsy, or a general state of
weakness, deformity, or sores, was sometimes inherited. It is,
however, possible that the mere injury introduced and encouraged the
growth of certain microbes, which, spreading through the organism,
sometimes reached the germ-cells, and thus transmitted a diseased
condition to the offspring." {286}

I suppose a microbe which made guinea-pigs eat their toes off was
communicated to the germ-cells of an unfortunate guinea-pig which
had been already microbed by it, and made the offspring bite its
toes off too. The microbe has a good deal to answer for.

On the case of the deterioration of horses in the Falkland Islands
after a few generations, Professor Weismann says:--

"In such a case we have only to assume that the climate which is
unfavourable, and nutriment which is insufficient for horses, affect
not only the animal as a whole but also its germ-cells. This would
result in the diminution in size of the germ-cells, the effects upon
the offspring being still further intensified by the insufficient
nourishment supplied during growth. But such results would not
depend upon the transmission by the germ-cells of certain
peculiarities due to the unfavourable climate, which only appear in
the full-grown horse."

But Professor Weismann does not like such cases, and admits that he
cannot explain the facts in connection with the climatic varieties
of certain butterflies, except "by supposing the passive acquisition
of characters produced by the direct influence of climate."

Nevertheless, in his next paragraph but one he calls such cases
"doubtful," and proposes that for the moment they should be left
aside. He accordingly leaves them, but I have not yet found what
other moment he considered auspicious for returning to them. He
tells us that "new experiments will be necessary, and that he has
himself already begun to undertake them." Perhaps he will give us
the results of these experiments in some future book--for that they
will prove satisfactory to him can hardly, I think, be doubted. He
writes:--

"Leaving on one side, for the moment, these doubtful and
insufficiently investigated cases, we may still maintain that the
assumption that changes induced by external conditions in the
organism as a whole are communicated to the germ-cells after the
manner indicated