LECTURE V. 239 



prudence or probable security one step far- 

 ther than Mr. Hunter has led me. I must 

 believe respiration to be essential to life, 

 and that life has the power, by its actions, 

 of maintaining and regulating temperature. 



Mr. Hunter suggested that the blood 

 ought, for numerous reasons, to be consi- 

 dered as a living fluid, and adds, " that the 

 blood has life, is an opinion I have started for 

 above thirty years, (which must have been 

 in the year 1760,) and have taught it, for 

 nearly twenty of that time, in my lectures." 

 I quote this passage merely to show how 

 early he had acquired those notions of life, 

 which I consider as the primary stimulus of 

 his meritorious and highly useful exertions^. 

 He wonders that this opinion had not been 

 more deeply impressed on the minds of 

 medical enquirers, because the blood un- 

 dergoes evident changes from variations in 

 the state of the health, and the actions of 

 the vessels. Life is generally attributed to 

 solids only, yet these are formed from the 

 blood, which could not give them what it 

 did not possess. He says, that in the years 



