EXPERIMENTS OF PHILIP. 1083 



Dr. Philip, who found that when inflammation 

 was produced in the transparent web of a frog's 

 foot, the fins and tail of fish, or in the mesen- 

 tery of a rabbit, by mechanical or chemical 

 irritants, the small vessels became enlarged, con- 

 gested with red blood, and its circulation more 

 and more languid, until at length it entirely 

 ceased. He also found, that when caused by 

 exposure to a cold current of air, the diameter 

 of the vessels was diminished, and the velocity 

 of the blood through them increased, on directing 

 upon the inflamed part the concentrated rays of 

 the sun from the concave reflector of his micro- 

 scope. (Exp. Inquiry, pp. 280. 288. 297. 381.) 

 Yet this last experiment seems not to have called 

 the attention of Dr. Philip to the important arid 

 very obvious conclusion, that caloric is the cause 

 of circulation ; and he maintains that blood is 

 impelled through the capillaries by virtue of 

 their own action ; so that when weakened by 

 cold, mechanical or chemical irritation, the velo- 

 city and momentum of the blood through them 

 must be diminished, or even wholly arrested in 

 extreme cases. But I have proved that the im- 



vein during inflammation than at other times, except when the 

 action of the heart and general circulation are greatly augmented. 

 On the contrary, in the worst forms of inflammation, it flows at 

 first with difficulty ; shewing that its motion has been retarded, 

 and that the power of the heart is inadequate to propel it onward, 

 until a portion of it is removed, when it runs more freely, and 

 changes to a brighter hue. 



