REGENERATION AND HEMORRHAGE. 



467 



suddenly by hemorrhage without producing a fatal result. The 

 extent of hemorrhage that may be recovered from safely has been 

 investigated upon a number of animals. Although the results 

 show more or less individual variation, it may be said that in dogs 

 a hemorrhage of from 2 to 3 per cent, of the body-weight* is re- 

 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 



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, ot the 

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

 immediately. 



the body-weight. If a hemorrhage has not been fatal, experi- 

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

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

 ume within a few hours in shght hemorrhages, and in from twenty- 

 four to forty-eight hours if the loss of blood has been severe; but 

 the number of red corpuscles and the hemoglobin are restored 

 more slowly, getting back to normal only after a number of days or 

 after several weeks. The accompanying curves illustrate the results 

 * Fredericq, "Travaux du Laboratoire" (Universite de Liege), 1, 189, 1885. 



