Observations on the Structure, and Mode of Growth, of the Grinding Teeth of the Wild Boar, and Animal Incognitum.

52

trary, punctures, dimples, and a poor appearance of the luminous
clouds,. the absence of ridges, nodules, large openings, and flats, de-
note a spare emission of heat, and may induce us to expect severe
seasons.

Pursuing this last idea, Dr. Herschel subjoins, at the end of his
paper, a comparative view of the best accounts that are to be met
•with of the appearances of the sun at particular periods as far back
as the middle of the seventeenth century, with the state of the sea-
sons during the same periods. Of the latter, the best information
could only be gathered from the state of vegetation, particularly of
com, of the price of which registers have been kept many years back :
and though this price be by no means an accurate criterion of the
quantity of corn produced, yet it is recurred to as the least objec-
tionable that could be obtained. The result of this review actually
leads to the conclusion, that the price of wheat has constantly risen
during the time the sun has been without spots ; and that it has
always fallen when those spots began to re- appear.

The Doctor seems aware of some fallacy in this mode of argumen-
tation; but he adds some hints by which several of the objections
might, he thinks, be obviated.

Observations on the Structure, and Mode of Growth, of the grinding
Teeth of the Wild Boar, and Animal incognitum. By Everard
Home, Esq. F.R.B, Read May 7, 1801. [Phil Trans. 1801,
1^.319.3

The author on a former occasion laid before the Society aii account
of certain peculiarities in the growth of the grinding teeth of the
Sus sethiopicus, and pointed out the similarity of their structure to
that of the elephant. Having since discovered that alike resemblance
extends also to the dentition of the wild boar, though in a less de-
gree, and at a later period of life, he Is pleased to communicate to
the Society, in his present paper, some further remarks on this cu-
rious subject.

We here learn, that in the species of the Sus, the first or tempo-
rary grinders are sixteen in number ; viz. four in each side of the
upper, and as many in the under jaw ; that these are shed in the usual
manner ; and that their places are supplied by larger teeth, rising
from the substance of the jaw, immediately under the old ones ;
that before these first teeth are shed, one of the more permanent
grinders is formed in the posterior part of each jaw, which, although
it be in its place with the first set, is yet to be considered as belong-
ing to the second ; that besides these five teeth, the rudiments of a
sixth are farmed in each jaw, which afterwards grows larger than the
preceding ones, the jaw increasing in size, so as to make room for
this as the posterior grinder ; that this tooth, when perfect, is double
the size of , the other grinders, its masticating surface having eight
fangs, BO that |t very much resembles two large grinding teeth in-
corporated into one ; that, in time, the rudiments of a seventh tooth

5S

appear in each jaw, but that the further progi'ess of these could not
be observed, none of the specimens the author has had opportunities
of inspecting, appearing to be more than seven years old.

Mr. Home proceeds next to observe, that the elephant, the Sus
sethiopicus, and the wild boar, are the only recent animals in which
he has hitherto met with so extensive a masticating surface of the
grinding teeth ; the human species only excepted, in which the mode
of dentition is somewhat upon the same principle as that of the wild
boar, with this difference, that the hindmost teeth, called, from the
late period of life at which they cut the gum, Dentes Sapientise, do
not exceed the others in size, and have often not sufficient room in
the jaw to come into their regular place. A conjecture is hence de-
rived, that when the period of man's life was longer than it is at
present, the growth of the posterior part of the jaw was continued
for a greater length of time, so as not only to make room for the
present, but perhaps also to admit of a succession of a still greater
number of additional grinders.

Upon comparing the grinders of the boar with the large fossil
teeth found on the banks of the Ohio, they were found so much alike,
both in their external appearance and internal structure, as to render
it more than probable that they are teeth of the same kind, only dif-
fering in size. Not so, however, those of the fossil skeleton some
time since found in South America, and described by M. Cuvier.
These were found so unlike those of the boar, or the above-men-
tioned incognitum, as to leave no doubt of its being an animal of a
different genus.

From the progressive mode of dentition above described, it is in-
ferred, that the animals to which it appears to be peculiar, have by
nature been intended for great longevity. This we know to be the
case in the elephant : and though opportunities have not yet offered
for ascertaining the term of life of the wild boar, some quotations
from ancient authors are here adduced, which indicate that boars of
enormous size have at different times existed ; whence the proba-
bility is inferred that their bulk must have been the growth of many
years.

Account of some Experiments on the Ascent of the Sap in Trees. In a
Letter from Thomas Andrew Knight, Esq. to the Right Hon, Sir
Joseph Banks, Bart. K,B. PM.S, Read May 14, 1801. {PhiL
Trans. 1801,^9.333.]

The author prefaces his paper by declaring that the cause of the
ascent of the sap in trees appearing to him not to have been as yet
satisfactorily accounted for, he resolved to enter on an experimental
inquiry on the subject ; and that having met with some facts of which
he had found no mention in any author, he flattered himself an account
of them might not be unacceptable to the Society.

The first experiments were made with a view to determine whether
the sap does actually, as has been thought by some, ascend along