424 BLOOD AND LYMPH. 



as possible and weighing the quantity of blood thus obtained, and 

 afterward washing out the blood-vessels with water and estimating 

 the amount of hemoglobin in the washings. The results are as 

 follows: Man, 7.7 per cent. (yV) of the body-weight; that is, a man 

 weighing 68 kgms. has about 5236 gms., or 4965 c.c., of blood in his 

 body; dog, 7.7 per cent.; rabbit and cat, 5 per cent.; new-born 

 human being, 5.26 per cent.; and birds, 10 per cent. The dis- 

 tribution of this blood in the tissues of the body at any time has 

 been estimated by Ranke,* 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 f 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.) 

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

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



* Taken from Vjerordt's "Anatomische, physiologische, und physikalische 

 Daten und Tabellen," Jena, 1893. 



fFredericq: "Travaux du Laboratoire" (University de Liege), 1, 189, 

 1885. 



