MOTION OF THE HEART AND BLOOD 



may be found why Nature, in larger adult animals, 

 filters the blood through the lungs instead of choosing 

 a direct path. No other way seems possible. It may 

 be the larger, more perfect animals are warmer and 

 when full grown their greater heat is thus more 

 easily damped. For this reason the blood may go 

 through the lungs, to be cooled by the inspired air 

 and saved from boiling and extinction.^ There may 

 be other reasons. To discuss and argue these points 

 would be to speculate on the function of the lungs. 

 I have made many observations on this matter, on 

 ventilation, and on the necessity and use of air, as 

 well as on the various organs in animals concerned 

 in these matters. Nevertheless I shall leave these 

 things to be more conveniently discussed in a separate 

 tract lest I seem to wander too far from the propo- 

 sition of the motion and function of the heart, and 

 to confuse the question. Returning to our present 

 concern, I shall go on with my demonstration. 



1912, p. 50.) He may have used opium preparations to give analgesia 

 but there is no evidence favoring this view. It is not Hkely that he 

 performed many experiments on higher animals, except such as were 

 caught wounded in the King's hunts. R. Hannah has painted such a 

 scene, where Harvey is demonstrating to Charles the heart of a deer 

 slain in the chase. 



' The innate heat was supposed to reside in the blood, and the older 

 theories on the heart beat and movement of the blood included the 

 idea that the blood boiled up in the heart, and "boiled over" into the 

 vessels, thus causing the heart beat and pulse. The function of respira- 

 tion was thus to cool the heart. It is peculiar that Harvey should have 

 permitted himself to utter this speculation when he so sarcastically 

 attacked the current ideas on respiration and the cooling of the blood 

 in the introduction. 



[59] 



