362 COOLING OF ANIMALS EXPOSED TO GREAT HEAT. 



Mechanical it is true, struck with the errours committed by those, who 

 been earned ^^ ^^^^ ^^^ ^ ^^^^ ^^^ ascribing every thing to mechanical 

 too far. Jaws, will not admit any explanation of this kind in the 



animal economy. They are of opinion, that the pheno- 

 mena, essentially connected with the exercise of life, must 

 depend on the laws that govern vitality; and not on phy- 

 sical laws, which have little apparent connection with the 

 former, and very frequently seem in opposition to them. 

 But is not this opinion founded on reasoning rather than ex- 

 Biit not wholly periment ? And if some of ihe phenomena of life appear 

 to be rejected. ^^ jjg Contradictory to those laws, to which inanimate bodies 

 are subject, must we thence infer, that it is the same with 

 all of them ? This reasoning, erroneous in itself, would be 

 contradictory to experience. Who, indeed, can over- 

 look the influence of physical causes in several of the phe- 

 nomena of the animal economy; such for instance as dis- 

 tinct vision, Avhich depends essentially on the refracting 

 powers of the humours of the eye; or the movements of 

 our limbs, in which our bones act as levers, our tendons as 

 cords? It is true, that physical causes alone are not suf- 

 ficient to produce these results, and vital causes* powerfully 

 concur in them; but the influence of the former is not the 

 Commonly less evident. Generally speaking it may be said, that there is 

 both act; scarcely a phenomenon of the animal economy, which is 



sometimes one not owing to both. Sometimes the influence of physical 

 predominating, causcs IS predominant, at others that of the vital; and fre- 

 sometimes the . . . , . ^ , , , , . • , • . i , , 



other. quently it IS difficult to determine with precision what be- 



longs to one, and what to the other. It is of no small con- 

 sequence, however, to attain this object ; and the researches 

 capable of leading to it may be ranked among the most im- 

 portant in physiology. If we can ever hope to ac- 



Vtal causes * When I speak of vital causes and vital laws, I do not mean to 



assert, that they are actually different from the general laws, that 

 govern inanimate matter, and independent of them : they are, 

 perhaps, only modifications of them ; but I am of opinion, that, 

 in the present state of science, we must admit them, if we would 

 acquire tolerably accurate ideas of the mode, in which the dif- 

 ferent functions of organic bodies are executed. We are yet far 

 from having reached the period, when many of the phenomena 

 exhibited by these bodies may be referred to the laws of physics. 



quira 



