CHAPTER XVII 



LYMPHATIC 

 SYSTEM 



Lymph tubes. 



Enlarged lymph gland. 



Hoiv teas the circulation of blood first demonstrated f What is the 

 relation of lymph to blood f What effect has alcohol on the heart f 



Historical survey of the circulation. The study of the circu- 

 lation was one of the first biological investigations that was con- 

 ducted experimentally. In the early seventeenth century, Galileo, 

 the Italian physicist, had performed and observed experiments on 

 falling bodies, and William Gilbert of England had experimented, 

 with electric and magnetic attractions. Due to their work and in- 

 fluence William Harvey (1578-1657) began to make some experi- 

 mental investigation in biology. The Greek anatomist, Galen 

 (131-201 A.D.), had taught that there was an ebb and flow of blood 

 within both veins and arteries throughout the body. He thought 

 that the left side of the heart contained blood which was vita- 

 lized by a mixture of animal spirits in the lungs. The veins were 

 supposed to contain crude blood. He believed that the blood 

 passed from the right to the left side of the heart through very 

 minute pores in the partition. It was also supposed that one kind 

 of blood flowed from the liver, to the right ventricle, to the lungs, 

 and then through the veins, while another kind of blood flowed 

 from the left ventricle to the lungs and then through the arteries. 

 In 1510, Leonardo da Vinci wrote a manuscript which included notes 

 and drawings of the heart and the blood vessels. He had studied 



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