CONTROL OF THE CIRCULATION. ?$ 



a little roll of wire screen), there will soon collect on the 

 wires a stringy substance. Thorough washing will soon 

 leave this colorless. It is fibrin. If the stirring has been 

 done thoroughly, the blood will no longer clot, no matter 

 how long it may stand. 



Liquid Blood and Coagulated Blood. The following 

 scheme shows the difference between the liquid blood and 

 the coagulated blood : 



( Serum 



Liquid Blood 



Plasma. 



( Fibrin 



Clot 



Coagulated Blood. 



Corpuscles 



Amount of Blood. The blood constitutes about one 

 thirteenth of the weight of the body. In a body weighing 

 one hundred and fifty pounds this would be about six 

 quarts. 



Chemical Reaction of Blood. Blood is alkaline. 



Specific Gravity of Blood. Blood is somewhat heavier 

 than water, owing to the salts and other matters dissolved 

 in it. 



Quantity of Blood in Different Organs (approximately). 

 i. One fourth is in the heart and the larger arteries 

 and veins (including those of the lungs). 



2. One fourth in the liver. 



3. One fourth in the skeletal muscles. 



4. One fourth in the other organs. 



The Lymph Spaces. We have seen that the capillaries 

 have very thin walls. Through their walls part of the 

 plasma of the blood soaks out, and is then called lymph. 

 It passes into irregular cavities in the tissue called lymph 

 spaces. Most of these lymph spaces are minute chinks or 



