the glass covers was to allow the animals to be inspected, without
disturbing the clay so as to admit external air or insects into the
cell. The limestone is so porous that it is easily permeable by water,
and probably also by air; the sandstone is very compact.

"On the 26th of November 1825, one live Toad was placed in each of the
above-mentioned twenty-four cells, and the double cover of glass and
slate placed over each of them, and cemented down by the luting of clay.
The weight of each Toad in grains was ascertained and noted by Dr
Daubeny and Mr Dillwyn at the time of their being placed in the cells;
that of the smallest was 115 grains, and of the largest 1185 grains. The
large and small animals were distributed in equal proportion between the
limestone and sandstone cells.

"These blocks of stone were buried together in my garden beneath three
feet of earth, and remained unopened until the 10th of December 1826, on
which day they were examined. Every Toad in the smaller cells of the
compact sandstone was dead, and the bodies of most of them so much
decayed that they must have been dead some months. The greater number of
those in the larger cells of porous limestone were alive. No. 1, whose
weight when immured was 924 grains, now weighed only 698 grains. No. 5,
whose weight when immured was 1185 grains, now weighed 1265 grains. The
glass cover over this cell was slightly cracked, so that minute insects
might have entered: none, however, were discovered in this cell; but in
another cell whose glass was broken, and the animal within it dead,
there was a large assemblage of minute insects; and a similar assemblage
also on the outside of the glass of a third cell. In cell No. 9, a Toad
which when put in weighed 988 grains, had increased to 1116 grains, and
the glass cover over it was entire; but as the luting of the cell within
which this Toad had increased in weight was not particularly examined,
it is probable there was some aperture in it by which small insects
found admission. No. 11 had decreased from 936 grains to 652 grains.

"When they were first examined in December 1826, not only were all the
small Toads dead, but the larger ones appeared much emaciated, with the
two exceptions above mentioned; we have already stated that these
probably owed their increased weight to the insects which had found
access to the cells, and become their food.

"The death of every individual of every size in the smaller cells of