feed. In general form they resemble little slugs, but are very much
narrower in proportion, and several of the species are beautifully
coloured with longitudinal stripes. Their structure is very simple:
near the middle of the under or crawling surface there are two small
transverse slits, from the anterior one of which a funnel-shaped and
highly irritable mouth can be protruded. For some time after the rest
of the animal was completely dead from the effects of salt water or any
other cause, this organ still retained its vitality.
I found no less than twelve different species of terrestrial Planariae
in different parts of the southern hemisphere. [3] Some specimens which
I obtained at Van Dieman's Land, I kept alive for nearly two months,
feeding them on rotten wood. Having cut one of them transversely into
two nearly equal parts, in the course of a fortnight both had the shape
of perfect animals. I had, however, so divided the body, that one of
the halves contained both the inferior orifices, and the other, in
consequence, none. In the course of twenty-five days from the
operation, the more perfect half could not have been distinguished from
any other specimen. The other had increased much in size; and towards
its posterior end, a clear space was formed in the parenchymatous mass,
in which a rudimentary cup-shaped mouth could clearly be distinguished;
on the under surface, however, no corresponding slit was yet open. If
the increased heat of the weather, as we approached the equator, had
not destroyed all the individuals, there can be no doubt that this last
step would have completed its structure. Although so well-known an
experiment, it was interesting to watch the gradual production of every
essential organ, out of the simple extremity of another animal. It is
extremely difficult to preserve these Planariae; as soon as the
cessation of life allows the ordinary laws of change to act, their
entire bodies become soft and fluid, with a rapidity which I have never
seen equalled.
I first visited the forest in which these Planariae were found, in
company with an old Portuguese priest who took me out to hunt with him.
The sport consisted in turning into the cover a few dogs, and then
patiently waiting to fire at any animal which might appear. We were
accompanied by the son of a neighbouring farmer--a good specimen of a
wild Brazilian youth. He was dressed in a tattered old shirt and
trousers, and had his head uncovered: he carried an old-fashioned gun
and a large knife. The habit of carrying the knife is universal; and
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