403 



lire powers of a different nature would be a contradiction in terms, for 

 it is only by its properties that any principle of action can be distin- 

 guished. 



He refers, in confirmation of these inferences, to the recent inves- 

 tigations of Mr. Faraday, from which it appears that electricity is 

 the agent in all chemical processes j to the facts which prove that all 

 the functions of the nervous influence, properly so called, are of a 

 chemical nature ; and also to the late experiments of Dr. Davy on 

 the Torpedo, tending to show that the electric power, peculiar to 

 electric animals, is a function of the brain, and thus affording direct 

 proof that the brain has the power of collecting and applying, even 

 according to the dictates of the will, the electric power. 



It farther appears, from the facts referred to in this paper, that, 

 whenever we can trace any analogy between the functions of the liv- 

 ing animal and the operations of inanimate nature, an agent belong- 

 ing to the external world is employed ; that these functions are the 

 results either of such agents acting on vital parts, or of vital parts 

 acting on them ; and that the sensorial functions, on the other hand, 

 in which no such analogy can be traced, are the effects of vital parts 

 acting on each other, and influencing each other by their vital pro- 

 perties alone. 



In the concluding part of the paper the author considers the vari- 

 ous functions of the living animal as forming two systems, in a great 

 measure distinct from one another, in each of which all its powers 

 are employed, but in very different ways : the object of the one of these 

 systems being the maintenance of the body itself; of the other, the 

 maintenance of its intercourse with the external world. The manner 

 in which the different powers of the living animal are employed in the 

 construction of each of these systems is pointed out 5 and the bonds 

 of union which exist between them, and thus form the living body into 

 a whole, no part of which can be affected without tending more or less 

 to affect every other, are considered. These bonds of union consist 

 chiefly in the employment of the same powers in the construction of 

 both systems, and in the function of respiration, which so extensively 

 influences all other functions both in health and disease, as pointed 

 out by the author in his papers on the nature of sleep and death, and 

 which differs from all the other vital functions in partaking of the sen- 

 sorial as well as of all the other powers of the living animal. 



5. " On the Respiration of Insects." By George Newport, Esq. 

 Communicated by P. M. Roget, M.D., Sec. R.S. 



Although a multitude of facts has been collected relating to the 

 physiology of respiration in insects, attention has seldom been directed 

 to the variations exhibited in this function in the different periods of 

 their existence. The author gives an account, in this paper, of the 

 anatomical and physiological peculiarities which he has noticed in va- 

 rious insects, in their three states of larva, pupa, and imago. He 

 traces all the several changes which the tracheae and spiracles undergo 

 during their transformations ; describing particularly the successive 

 development of the air vesicles in connexion with the power of flight. 



