ao6 CIRCULATORY SECT. XXIII. i. f , 



SECT. XXIII. 



OF THE CIRCULATORY SYSTEM. 



1. The heart and arteries lave no antagonijl mufeles. Feins abforb 

 the blood* propel it forwards, and diftend the heart ; contraction of 

 the heart diftendt the arteries. Vena portarum. II. Glands which 

 take their fluids from the blood With long necks > andjhort necks* 

 III. Abforbent fyftem. IV. Heat given out from glandular fe~ 

 ceetions* Blood changes colour in the lungs and in the glands and 

 capillaries V. Blood is ab for bed by veins , ar chyle by la&eal veffe/s 9 

 othe> wife they could not join their Jlr earns* IV. Two kinds ofjlim- 

 ulu* , agreeable and difagreeable. Glandular appetency. Glands 

 originally pujjejjed fenfation* 



I. i. We now ftep forwards to illuftrate fome of the phaenom- 

 na of difeafes, and to trace out their moft efficacious methods 

 of cure j and (hall commence the fubjecl with a ihort defcrip- 

 tion of the circulatory fyftem. 



As the nerves, whofe extremities form our various organs of 

 fenie and rnircks, are all joined, or communicate, by means of 

 the brain, for the convenience perhaps of the diftribution of a 

 fubtile ethereal fluui for the purpoie of morion ; fo all thofe 

 veflelb of the body, which carry the grofler fluids for the purpo- 

 fes of nutrition, communicate with each other by the heart. 



The heart and arteries are hollow mufcles, and are therefore 

 indued with power of contraction in confequence of ftimulus t 

 like all other mulcular fibres ; but, as they have no antagonift 

 mufeles, the cavities of the vcflels, which they form, would re- 

 main for ever clofed, after they have contra&ed themfelves, un- 

 lefs fome extraneous power be applied to again diftend them. 

 This extraneous power in refpecl: to the heart is the current of 

 blood which is perpetually abibrbed by the veins from the various 

 glands and capillaries, and pufhed into the heart by a power prob- 

 ably very fimilar to that, which raifes the fap in vegetables in 

 the fpring, which, according to Dr. Hale's experiment on the 

 ftump of a vine, exerted a force equal to a column of water 

 above twenty feet high* This force of the current of blood in 

 the veins is partly produced by their abforbent power, exert- 

 ed at the beginning of every fine ramification ; which may be 

 conceived to be a mouth abforbing blood, as the mouths of the 

 la&eals and lymphatics abforb chyle and lymph. And partly 

 by their intermitted compreffion by the pulfations of their gener- 

 ally concomitant arteries \ by which the blood is perpetually pro- 

 pelled 



