PART II 

 NUTRITION OF THE TISSUES 



SECTION VI 



FLUIDS BATHING THE TISSUES 



BLOOD AND LYMPH 



THE blood carries the necessary nourishment to the tissues, 

 and receives their waste products. But it is enclosed in a 

 closed system of vessels, and does not come into direct rela- 

 tionship with the cells. Outside the blood vessels, and bath- 

 ing the cells, is the lymph which plays the part of middleman 

 between the blood and the tissues, receiving nourishment 

 from the former for the latter, and passing the waste from 

 the latter into the former. 



A. BLOOD. 



The various physical, chemical, and histological characters 

 of blood must be practically investigated. 



I. General Characters. 



Colour. Blood changes its colour from purple to cinnabar 

 red on shaking with air, showing that the pigment of the 

 blood may exist in two conditions. Elements of Blood. 

 Microscopic examination shows that blood is composed of a 

 clear fluid (Liquor Sanguinis or Plasma) in which float 

 myriads of small disc-like yellowish-red cells (Erythrocytes), 

 and a smaller number of greyish cells (Leucocytes), and 

 certain more minute grey particles (Blood Platelets). The 

 Opacity of Blood is due to the erythrocytes. When the 

 pigment is dissolved out of them by water, and they are 



