that we cannot dwell longer on this curious part of the lecture, espe-
cially where it treats of the combination, by means of nerves between
animated and what may be deemed inanimate matta, as in the in-
stances of bones, shells, teeth, and other extravascular and insensible
substances, which, when completed, are no longer alterable by the
animal functions.
Sect. 3. Of the connezions between the functions of muscles and the temperature and respiration of the animal.——That different parts of an animal are susceptible of different degrees of temperature, is a fact which stands in no need of demonstration; and it is equally obvious that every animal, besides being susceptible of the external changes of temperature, possesses also the power of generating heat within itself. This last-mentioned power is ascribed, in a great measure, to respir 'on; and this opens a field of in what manner and to at degree the difi'erent classes of animals are possessed of that faculty. In this disquisition we find, among other interesting facts, a curious account in what manner hybernating animals are enabled to subsist several months without respiration.
The irritability of the heart, we are next told, is inseparath con- nected with respiration, and the blood appears to be the medium of conveying heat to the different parts of the body; and hence it is naturally inferred, that the changes of animal temperature in the same individual are always connected with, and proportionate to, the velocity of the circulation. After death, the blood of an animal is presently coagulated, and the muscles are usually contracted; but, from some observations here stated, it appears that the final con- traction of muscles is not inseparable from coagulation of the blood within them, nor of a change in the reticular membrane. Lastly, it is asserted, that the reiterated influx of blood is not essential to muscular irritability; since the limbs of animals, separated from the body, continue for a long time afterwards capable of contractions and relaxations.
Sect. 4. Of the application of chemistry to this subject.—Our lecturer asserts, under this head, that the constituent elements of both animal and vegetable substances are not separable by any chemical process hitherto instituted, in such a manner as to admit of a synthetical re-combination: and he maintains, that, until such a recombination can be effected, all chemical discussions-and investigations on the matter of muscles are not liker to afford any conclusive illustration.
Sect. 5. Facts and experiments tending to support and illustrate the preceding arguments.—We meet here with a number of observations on the heat of the blood and viscera of animals of different classes; also on the effects of crimping fish, which produces not only a sensible rigidity or contraction, but also an increase of specific gravity, in the muscles. Muscular fibres of quadrupeds, being immersed in Water of a low temperature, gave also manifest proofs of contractions occasioned thereby. In the heat of 100°, the muscles of cold-blooded animals, and at 110° those of the warm-blooded, fall into the con~
