230 The Rise of the Modem [lect. 



" water impregnated with a volatile fatty exhalation and not 

 " free from saline matter." 



The subject I of animal heat is so closely connected with 

 respiration that it will be convenient to note here what Haller 

 has to say about this. He expounds in the first place what 

 may be called the chemical theories of animal heat, the fer- 

 mentation in the heart, as put forward by van Helmont, and 

 the effervescence arising from the meeting of the old used-up 

 blood, spoken of as venous blood, and the fresh acid chyle, as 

 put forward by Sylvius. He merely touches in a very scanty 

 manner only on the more exact chemical view of Mayow. But 

 he goes on to say that "towards the close of the preceding 

 "(seventeenth) century greater attention was paid to the 

 " properties of solid parts, and the importance attached to 

 " chemical causes (such as van Helmont and Sylvius had 

 " brought to the front) somewhat fell off." Hence there came 

 into more general acceptance the physical view that the heat of 

 the body was due to the friction of the blood as it was driven 

 through the blood vessels, the view held as we have just seen 

 by Stahl. 



Haller discusses all the various arguments for and against 

 these several views, and concludes as follows : 



" So far then it seems most probable that the blood is 

 "certainly warmed by its movement, but it is by no means 

 " clear why it should be thus warmed to a higher degree than 

 • water would be under like circumstances, or why the tem- 

 "perature is never varied beyond certain narrow limits." 



I have given this brief sketch of Haller' s exposition in order 

 to shew how little advance has been made since the days of 

 the English School of which I spoke in a preceding lecture. 

 Perhaps one ought rather to say how things had gone back, for 

 the lead offered by Mayow as it had been rejected by those 

 coming between him and Haller, so it was rejected by Haller 

 himself. 



Meanwhile the first step in the new progress which before 

 long was to be made had been taken, and that in Mayow's 

 country, in England, or rather in Great Britain. 



Well known to Haller, though perhaps not fully appreciated 



