HISTORY OF PHYSIOLOGY. 11 



Galen was the medical adviser of the imperial family itself 

 and so probably the most learned physician of Rome. It 

 is due to the genius of Galen to have put an end to some 

 of the misconceptions clustering around the idea of the 

 pneuma and the arteries. He established the fact that the 

 arteries normally contain blood. He describes that having 

 laid bare the axillary artery of an animal while it was pul- 

 sating regularly, and so according to the established notion 

 containing pneuma, he pricked it with a fine needle, and 

 found that in the very first instance blood came out, and 

 TLO\. pneuma, followed later by blood, which had soaked in. 

 When such a pulsating artery was cut the blood spurted 

 out forcibly at once, showing that it must have contained 

 blood before opening. What a simple and conclusive exper- 

 iment ! and yet it had taken the world centuries to think of 

 it. He also described the heart very carefully, and even 

 investigated successfully the changes in the circulation at 

 birth, having found the foramen ovale and the duct of 

 Botallus (duct us arteriosus] , and noted tke closing of the 

 former and the atrophy of the latter. (See chapter on 

 "Changes of the Circulation at Birth.") The discovery 

 of the true blood-carrying function of the arteries was 

 another tremendous step in the right direction, but in trying 

 to work out his idea of the system of blood vessels Galen was 

 led into several new misconceptions. From an historical 

 standpoint, however, they are of peculiar interest. Galen 

 made the liver the seat of the elaboration of the blood. 

 The portal circulation carries the foods from the stomach 

 and intestines to the liver (and in this he was correct) and 

 by the liver this food material was transformed into blood. 

 From the liver two vessels arose, one running downward to 

 the lower part of the trunk, and lower extremities ; the other 

 running upward to the heart. (In this way he had inter- 

 preted the large vena cava running through the liver to the 

 heart.) Through the right side of the heart the ascending 

 vessel was extended to the head and upper part of the body 

 (our descending vena cava and innominate veins) and 



