114 SEVENTEENTH CENTURY. pt. hi. 



circulation of the blood in 1628. Yet none of the older 

 physicians would believe he was right, and Harvey told a 

 friend that he lost many patients in consequence of his new 

 doctrine. It is greatly to the credit of the unfortunate King 

 Charles I., who was reigning at this time, and whose private 

 physician Harvey was, that he gave him many opportunities 

 of making physiological experiments on the animals in the 

 royal parks, and took great interest in his discoveries. 

 Harvey wrote several other valuable books, and traced the 

 development of the chicken in the ^%g. He was of a very- 

 gentle and modest disposition, and disliked controversy so 

 much that he could scarcely be persuaded to publish his 

 later investigations when he found what disputes were occa- 

 sioned by his great discovery of the circulation of the 

 blood. He died in 1657, in his eightieth year. 



Discovery of the Vessels which carry Nourishment to 

 the Blood, 1622-1649. — Harvey's doctrine of the circulation 

 of the blood was the real starting-point oi physiology^ or the 

 science of living bodies, and when the true action of the arte- 

 ries and veins was known, many other vessels of the body were 

 soon better understood. The most important of these were 

 the vessels which carrj- nourishment from all parts of the body 

 to make fresh blood. In 1622 Gaspard Asellius, Professor 

 of Anatomy at Pavia, saw a white fluid flowing from some 

 thread-like tubes in the body of a dog which he was dis- 

 secting. This dog had been eating food just before he died, 

 and Asellius found that the fluid came from the intestines 

 and was the nourishing matter of the food. He called these 

 fine tubes lacteals, because the fluid in them looked 

 like milk. Some years later, in 1647, Jean Pecquet, an 

 anatomist of Dieppe, discovered that these lacteah empty 

 themselves into a large tube called the thoracic duct^ which 



