144 HISTORY OF PHYSIOLOGY. 



been pointed out and confessed 19 without acrimony, if, in times ol 

 revolution, mildness and moderation were possible; but an impaticrct 

 of the superstition of tradition on the part of the innovators, and ar; 

 alarm of the subversion of all recognized truths on the part of the 

 established teachers, inflame and pervert all such discussions. Vesa- 

 lius's main charge against Galen is, that his dissections were performed 

 upon animals, and not upon the human body. Galen himself speaks 

 of the dissection of apes as a very familiar employment, and states that 

 he killed them by drowning. The natural difficulties which, in 

 various ages, have prevented the unlimited prosecution of human 

 dissection, operated strongly among the ancients, and it would have 

 been difficult, under such circumstances, to proceed more judiciously 

 than Galen did. 



I shall now proceed to the history of the discovery of another *nd 

 less obvious function, the circulation of the blood, which belongs to 

 modern times. 



CHAPTER II. 

 DISCOVERY OF THE CIRCULATION OF THE BLOOD. 



Sect. 1. Prelude to the Discovery. 



r 



blood-vessels, the veins and arteries, are as evident and peculia 

 in their appearance as the muscles ; but their function is by no 

 means so obvious. Hippocrates 1 did not discriminate Veins and Ar- 

 teries ; both are called by the same name ($\s[3e$) ; and the word 

 from which artery comes (dpryjph]) means, in his works, the windpipe. 

 Aristotle, scanty as was his knowledge of the vessels of the body, has 

 yet the merit of having traced the origin of all the veins to the heart- 

 He expressly contradicts those of his predecessors who had derived 

 the veins from the head ; 2 and refers to dissection for the proof. If 

 the book On the Breath be genuine (which is doubted), Aristotle was 

 aware of the distinction between veins and arteries. " Every artery," 



19 Cuv. Lefons sur VHist. des Sc. Nat. p. 25. 



1 Sprengel, i. 383. 2 Hut. Animal, iii. 8. 



