A HISTORY OF SCIENCE 



Among the anatomists who probably discovered 

 these valves was Michael Servetus (1511-1553); but 

 if this is somewhat in doubt, it is certain that he dis- 

 covered and described the pulmonary circulation, and 

 had a very clear idea of the process of respiration as 

 carried on in the lungs. The description was con- 

 tained in a famous document sent to Calvin in 1545 a 

 document which the reformer carefully kept for seven 

 years in order that he might make use of some of the 

 heretical statements it contained to accomplish his 

 desire of bringing its writer to the stake. The awful 

 fate of Servetus, the interesting character of the man, 

 and the fact that he came so near to anticipating the 

 discoveries of Harvey make him one of the most 

 interesting figures in medical history. 



In this document which was sent to Calvin, Servetus 

 rejected the doctrine of natural, vital, and animal 

 spirits, as contained in the veins, arteries, and nerves 

 respectively, and made the all-important statement 

 that the fluids contained in veins and arteries are the 

 same. He showed also that the blood is "purged from 

 fume" and purified by respiration in the lungs, and 

 declared that there is a new vessel in the lungs, * ' formed 

 out of vein and artery." Even at the present day 

 there is little to add to or change in this description of 

 Servetus' s. 



By keeping this document, pregnant with advanced 

 scientific views, from the world, and in the end only 

 using it as a means of destroying its author, the 

 great reformer showed the same jealousy in retard- 

 ing scientific progress as had his arch-enemies of 

 the Inquisition, at whose dictates Vesalius became 



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