296 THE POPULAR SCIENCE MONTHLY. 



illustrious Aristotle, being the son of one of his daughters. It is said 

 that he was so fond of anatomical pursuits that he retired from his prac- 

 tice in Alexandria, where he had settled, the better to gratify his taste. 

 He wrote several treatises which are lost, and all we possess of his 

 writings are a few fragments preserved in the works of Galen. From 

 these we learn that he gave names to the auricles of the heart. He 

 declared that the veins only were blood-vessels, and that the arteries, 

 as their name implies, were air-vessels. The sole purpose of breath- 

 ing was to fill the artei-ies with air; the air distended the arteries 

 and made them beat, the air caused the pulse. The air, once in 

 the left ventricle of the heart, became the vital spirits. The office 

 of the veins was to convey blood to the extremities. Wlien the 

 veins carried blood only and the arteries were filled with vital spirits, 

 then perfect health was maintained ; but the entrance of blood into 

 the arteries, which he admitted to sometimes occur, was abnormal 

 and the source of disease fevers when it entered some noble part or 

 into a great artery, and inflammations when it was found in the less 

 noble parts or in the extremities of the arteries. Thus it is seen that 

 a stupendous error was established on a mighty authority. This error 

 Avas destroyed by Galen four hundred years subsequently to the time 

 of Erasistratus. 



Claudius Galen (a. d. 131), next to Hippocrates the most cele- 

 brated physician the world ever produced, was born at Pergamus, in 

 Asia Minor, about the year of our Lord 131, and educated in anatomy 

 and medicine at Alexandria, then the most famous school in the world. 

 At the age of thirty-four he settled at Rome, where he distinguished 

 himself as a skillful practitioner, and became the physician to the Em- 

 peror Marcus Aurelius. The period of his death is not known, but it is 

 stated that he was still living in the reign of Septimius Severus. Galen 

 was a voluminous writer. A considerable number of his works are 

 lost, and yet eighty-two treatises, more or less complete, survive and 

 are in print. Tlie writer of this sketch felicitates himself in the pos- 

 session of a fine copy of the " Editio Princeps," in five ponderous folios, 

 printed in Greek, by the celebrated Aldine press, at Venice, 1525. 

 For a period of nearly fourteen centuries this vast mass more volu- 

 minous than the entire Bible was copied and recopied with the pens 

 of scribes ! Who can duly appreciate the value of the press ? Galen 

 proved that the arteries are blood-vessels, and thus destroyed the error 

 of Erasistratus. He said, when an artery is opened, blood alone 

 gushes out and no air. He tied an artery at two places a little distance 

 apart, and on opening the vessel found it filled with blood only. The 

 followers of Erasistratus wanted to know how the air from the lungs 

 entered all parts of the body, to whom Galen replied that the air 

 entered the lungs to cool the blood, after which it was expelled. This 

 theory was held so late as the last century, even by the renowned 

 physiologist Albrecht von Haller. Galen declared the pulse to be the 



