98 CIRCULATION OF THE BLOOD. 



can the extremities be warmed in no way, save by circulation ; 

 the chilled blood, which has lost its spirit and heat, being driven 

 out, and fresh, warm, and vivified blood flowing in by the arte- 

 ries in its stead, which fresh blood cherishes and warms the parts, 

 and restores to them sense and motion ; nor could the extremities 

 be restored by the warmth of a fire or other external heat, any 

 more than those of a dead body could be so recovered : they are 

 only brought to life again, as it were, by an influx of internal 

 warmth. And this indeed is the principal use and end of the 

 circulation ; it is that for which the blood is sent on its cease- 

 less course, and to exert its influence continually in its circuit, 

 to wit, that all parts dependent on the primary innate heat may 

 be retained alive, in their state of vital and vegetative being, and 

 apt to perform their functions ; whilst, to use the language of 

 physiologists, they are sustained and actuated by the inflowing 

 heat and vital spirits. Thus, by the aid of two extremes, viz. 

 cold and heat, is the temperature of the animal body retained 

 at its mean. For as the air inspired tempers the too great 

 heat of the blood in the lungs and centre of the body, and effects 

 the expulsion of suffocating fumes, so in its turn does the hot 

 blood, thrown by the arteries into all parts of the body, cherish 

 and nourish and keep them in life, defending them from ex- 

 tinction through the power of external cold. 



It would, therefore, be in some sort unfair and extraordinary 

 did not every particle composing the body enjoy the advantages 

 of the circulation and transmutation of the blood ; the ends for 

 which the circulation was mainly established by nature would 

 no longer be effected. To conclude then: you see how cir- 

 culation may be accomplished without confusion or admixture 

 of humours, through the whole body, and each of its indivi- 

 dual parts, in the smaller as well as in the larger vessels ; and 

 all as matter of necessity and for the general advantage; with- 

 out circulation, indeed, there would be no restoration of chilled 

 and exhausted parts, no continuance of these in life ; since it is 

 apparent enough that the whole influence of the preservative 

 heat comes by the arteries, and is the work of the circulation. 



It, therefore, appears to me that the learned Riolanus speaks 

 rather expediently than truly, when in his Enchiridion he denies 

 a circulation to certain parts ; it would seem as though he had 

 wished to please the mass, and oppose none; to have written with 



