DISCOVERY OF CIRCULATION OF THE BLOOD. 295 



the exploits of conquering heroes, and yet pass almost unnoticed the 

 achievements of men of science. Few persons are at all acquainted 

 with the history of when and how, through a series of successive 

 revelations, this truly wonderful function came to be thoroughly 

 understood. It is a long and delightful story if followed through all 

 its details, which I shall, however, endeavor to cut short in relating 

 it to persons outside of the medical profession. We are obliged to 

 glance back through several centuries and make the acquaintance of 

 nearly a score of anatomical celebrities, who have each contributed 

 some observation or discovery leading to the final comprehension and 

 complete interpretation of God's beautiful but simple method of cir- 

 culating the vital fluid and keeping it ever replenished and pure. 



The pathway to the climax of this discovery was not only long 

 but rugged, hedged in by deeply-rooted errors, and obscured by rank 

 prejudices ancient and wide-spread. The errors must be destroyed, 

 the clouds dispelled, parts carefully observed; the explorers must 

 work slowly and cautiously, and what is discovered must be explained. 

 Thus it came to pass that anatomists discovered one thing after an- 

 other, and little by little the light of truth dawned upon their minds, 

 wherewith they saw and gave the world sensible ideas of the uses of 

 parts, when eventually " the immortal Harvey," the crowning light, 

 the clear-headed philosopher, the Newton of physiology, drew the 

 simple chart of the double circulation. This event took place two 

 hundred and fifty-seven years ago, for it was in 1619 that Harvey 

 completed the discovery. He made no haste to tell the world what 

 he had done, except what the individuals of his classes learned from 

 his lectures, for he taught his discoveries ten full years before he pub- 

 lished his modest but wonderful little book " Concerning the Motion 

 of the Heart and Blood in Living Creatures," printed in Latin at 

 Frankfort-on-the-Main, in a thin quarto of only seventy-two pages, in 

 the year of grace 1628. 



I propose to give a brief account of the antecedent errors and 

 discoveries to the time of Harvey that of Erasistratus, who taught 

 that the arteries were air-vessels ; of Galen, who demonstrated that 

 they are blood-vessels as well as the veins ; of Vesalius, who convinced 

 the world that Galen erred in declaring that holes existed in the par- 

 tition between the two sides of the heart; of Servetus, Columbus, and 

 Caesalpinus, who, quite independently of each other, discovered the 

 circulation through the lungs ; of Fabricius, who discovered the valves 

 in the veins ; of Harvey, who first comprehended the entire circula- 

 tion; of Asellius,who discovered the lacteals ; Pecquet, the receptacle 

 of the chyle ; Rudbeck, the lymphatics of the liver ; and, lastly, of 

 Thomas Bartholin, who discovered the lymphatics of the whole 

 body. 



Erasistratus (300-260 b. c), a Greek physician and anatomist, of 

 lulis (the modern Zea), in the island of Ceos, was the grandson of the 



