440 Proceedings of the Ohio State Academy of Science 



the cause of the beat of the arteries but he considered the 

 arteries to carry only air. He compared the walls of the ar- 

 teries with those of the veins and described the connection of 

 the heart with the lungs calling the vessel leading from the 

 right ventricle to the lungs the ARTERIAL VEIN and the 

 one leading from the lungs to the left side of the heart the 

 Venous Artery. 



Science is indebted to Erasistratus for the discovery of 

 the valves in the heart and their function in the circulation. 

 It is also supposed that he saw the lacteals, which are a part 

 of the lymphatic circulation. There is no doubt that the 

 Greeks recognized two kinds of vessels but the fact that they 

 considered the arteries to contain only air shows that they 

 knew nothing of their true function. This can be accounted 

 for from the fact that after death the arteries contain no blood 

 as a usual thing, and from the supposition that these arteries 

 had their origin in the trachea, hence the name "tracheal ar- 

 tery." Erasistratus traced the air from the trachea through 

 the arteries to all parts of the body. During the next four 

 hundred years human dissection, even in the Alexandrian 

 school, gradually fell into disuse, but in the later part of this 

 era there arose a man that was destined to become so world 

 renowned that his word was not disputed in any particular 

 for the next succeeding thirteen hundred years. Galen was 

 born in 130 A. D., went to Alexandria at sixteen years of age 

 and was practicing medicine at the age of twenty. He spent 

 many years at different times in his life in Egypt studying 

 anatomy. His dissections were limited to work upon the low- 

 er animals, but by ligating an artery in two places and open- 

 ing it between the ligatures he showed that they contained 

 blood, not air. This shows the great advantage of vivisection. 

 The importance of this experiment can not be over-estimated 

 for with the behef that the arteries carried air the true circu- 

 lation could never have been discovered. 



Galen did not believe with Erasistratus that the air en- 

 tered the body but that it was rejected at once after it had 



