REGENERATION AFTER HEMORRHAGE. 437 



The average results obtained from numerous experiments are as 

 follows: The ratio of weight of blood to weight of body is, in the 

 dog, 7.7 per cent.; rabbit and cat, 5 per cent.; birds, 10 per cent. 

 On man we have upon record tw r o determinations on guillotined 

 criminals made by Bischoff, which gave 7.7 and 7.2 per cent. 

 Haldane and Smith,* however, have devised a modification of 

 Grehant's carbon monoxid method, which they have applied to 

 living men. The results of some 74 experiments gave them an 

 average value of only 5 per cent, for man. The distribution of 

 this blood in the tissues of the body at any time has been esti- 

 mated by Rankest from experiments on freshly killed rabbits, as 

 follows : 



Spleen 0.23 per cent. 



Brain and cord 1.24 " 



Kidneys 1.63 " 



Skin 2.10 " 



Intestines 6.30 " 



Bones 8.24 " 



Heart, lungs, and great blood-vessels 22.76 " 



Resting muscles 29.20 " 



Liver 29.30 " 



It will be seen from inspection of this table that in the rabbit the 

 blood of the body is distributed at any one time about as follows: 

 One-fourth to the heart, lungs, and great blood-vessels; one-fourth 

 to the liver; one-fourth to the resting muscles; and one-fourth to the 

 remaining organs. 



Regeneration of the Blood after Hemorrhage. A large 

 portion of the entire quantity of blood in the body may be lost 

 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 J 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 

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

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



* Haldane and Smith, " Journal of Physiology," 1900, xxv., 331. 



f Taken from Vierordt's " Anatomische, physiologische, und physikalische 

 Daten und Tabellen," Jena, 1893. 



J Fredericq: "Travaux du Laboratoire " (Universite de Liege), 1, 189, 

 1885. 



