165 



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 matter, 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 connexions 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 respiration ; and this opens a field of inquiry, in what manner 

 and to what degree the different 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 inseparably 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 lec- 

 turer 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 syn- 

 thetical re-combination : and he maintains, that, until such a re- 

 combination can be effected, all chemical discussions and investiga- 

 tions on the matter of muscles are not likely 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 sen- 

 sible 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- 



