72 BLOOD. 



CONVERSATION IV. 



Circulation the Hood connection of circulation with 

 respiration blood-vessels heart, arteries, veins-~- 

 motion of the heart anastomosis of arteries the 

 pulse influence of disease on the pulse the lesser 

 or pulmonic, greater or systemic circulation capil- 

 lary system inflammation adhesion . 



Emily. To day we are to have some account of the 

 circulation; but I hope you will first favour me with an 

 .explanation of this term. I cannot conceive what this 

 allusion to a circle can mean. 



Dr. B. The function derives its name from the cir- 

 cumstance that the organs are joined together in such a 

 way that there is properly neither beginning nor end ; but as 

 it regards the function itself, they are connected in a com- 

 plete circle. Their use in the vital economy is to con- 

 vey different materials from one part of the system to 

 another ; to receive the chyle from the thoracic duct 

 and expose it to the action of the respiratory organs; 

 to take up particles of the body which are no longer fit- 

 ted for its purposes, and carry . them to the excretory 

 vessels to be thrown out of the system ; and finally, to 

 repair the waste of the organs with suitable materials of 

 supply. The fluid which they contain, thus made up of 

 heterogeneous materials, is called the blood, and is found 

 in all animals that possess a circulating system, though 



