470 



BLOOD AND LYMPH. 



covered from easily, while a loss of 4.5 per cent., more than half 

 the entire blood, will probably prove fatal. In cats a hemorrhage 

 of from 2 to 3 per cent, of the body-weight is not usually followed 

 by a fatal result. Just what percentage of loss may be borne by the 

 human being has not been determined, but it is probable that a 

 healthy individual may recover without serious difficulty from the 

 loss of a quantity of blood amounting to as much as 3 per cent, of 



2SDay. 



100 Erythrocytet. 



Hemoglobin. 



Leucocyte*. 



Fig. 187. To show the effect of hemorrhage upon the number of red and white cor- 

 puscles and the amount of hemoglobin. (Dawson.) The ordinates express the numbers 

 of corpuscles and also the percentages of hemoglobin as stated in the figures to the left. 

 The abscissas give the days after hemorrhage. The experiment was made upon a dog of 

 8.1 kgms. The hemorrhage, which lasted 2.3 minutes, was equal to 4.3 per cent, of the 

 body-weight. An equal amount of physiological saline (NaCl, 0.8 per cent.) was injected 

 immediately. 



the body-weight. It is known that if liquids that arc isotonic to 

 the blood, such as physiological saline (NaCl, 0.7 to 0.9 per cent.) 

 or Ringer's solution, are injected into the veins immediately after 

 a severe hemorrhage, recovery is more certain; in fact, it is 

 possible by this means to restore persons after a hemorrhage that 

 would otherwise have been fatal. By an infusion of this kind, 

 particularly if at or somewhat above the body temperature, the 

 heart beat is increased, the volume of the circulating liquid is 

 brought to an amount sufficient to maintain approximately normal 

 conditions of pressure and velocity, and the red corpuscles that still 

 remain are kept in more rapid circulation and are thus utilized more 

 completely as oxygen carriers. If a hemorrhage has not been fatal, 

 experiments on lower animals show that the plasma of the blood is 

 regenerated with some rapidity, the blood regaining its normal vol- 



