secretion with more difficulty than dentine, as might have been
expected from its extreme hardness; and both with more difficulty than
ordinary bone. After the process of dissolution has once commenced, it
is carried on with greater ease; this may be inferred from the leaves,
to which the fragments were transferred, becoming in all four cases
strongly inflected in the course of a single day; whereas the first set
of leaves acted much less quickly and [page 108] energetically. The
angles or projections of the fibrous basis of the enamel and dentine
(except, perhaps, in No. 4, which could not be well observed) were not
in the least rounded; and Dr. Klein remarks that their microscopical
structure was not altered. But this could not have been expected, as
the decalcification was not complete in the three specimens which were
carefully examined.
Fibrous Basis of Bone. I at first concluded, as already stated, that
the secretion could not digest this substance. I therefore asked Dr.
Burdon Sanderson to try bone, enamel, and dentine, in artificial
gastric juice, and he found that they were after a considerable time
completely dissolved. Dr. Klein examined some of the small lamellae,
into which part of the skull of a cat became broken up after about a
week s immersion in the fluid, and he found that towards the edges the
matrix appeared rarefied, thus producing the appearance as if the
canaliculi of the bone-corpuscles had become larger. Otherwise the
corpuscles and their canaliculi were very distinct. So that with bone
subjected to artificial gastric juice complete decalcification precedes
the dissolution of the fibrous basis. Dr. Burdon Sanderson suggested to
me that the failure of Drosera to digest the fibrous basis of bone,
enamel, and dentine, might be due to the acid being consumed in the
decomposition of the earthy salts, so that there was none left for the
work of digestion. Accordingly, my son thoroughly decalcified the bone
of a sheep with weak hydrochloric acid; and seven minute fragments of
the fibrous basis were placed on so many leaves, four of the fragments
being first damped with saliva to aid prompt inflection. All seven
leaves became inflected, but only very moderately, in the course of a
day. [page 109] They quickly began to re-expand; five of them on the
second day, and the other two on the third day. On all seven leaves the
fibrous tissue was converted into perfectly transparent, viscid, more
or less liquefied little masses. In the middle, however, of one, my son
saw under a high power a few corpuscles, with traces of fibrillation in
the surrounding transparent matter. From these facts it is clear that
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