QUANTITY OF BLOOD. 325 



to give a brief summary of the results, still the changes in the blood in 

 disease must be of the greatest importance. 



The quantity of blood is indeed somewhat variable in different species of 

 animals and in different conditions of the body; in general we consider 

 the entire quantity of blood in adults as about J^-j^ of the weight of the 

 body, and in new-born infants about -fa. HALDANE and LORRAIN SMITH/ 

 who have determined the quantity of blood by a new method, find in 

 fourteen persons that it varies between ^ and -^ of the weight of the body. 

 According to the same method OERUM 2 has determined the quantity 

 of blood in men as about -^ and in women -^ of the weight of the body. 

 Fat individuals are relatively poorer in blood than lean ones. During 

 inanition the quantity of blood decreases less quickly than the weight 

 of the body (PANUM 3 ), and it may therefore be also proportionally greater 

 in starving individuals than in well-fed ones. 



By careful bleeding the quantity of blood may be considerably dimin- 

 ished without any dangerous symptoms. A loss of blood amounting 

 to one-fourth of the normal quantity has as a sequence no lasting 

 sinking of the blood-pressure in the arteries, because the smaller arteries 

 accommodate themselves to the small quantities of blood by con- 

 tracting (WORM MtiLLER 4 ). A loss of blood amounting to one-third 

 of the quantity reduces the blood-pressure considerably, and a loss of 

 one-half of the blood in adults is dangerous to life. The more rapid the 

 bleeding the more dangerous it is. New-born infants are very sensitive 

 to loss of blood, and likewise fat, old, and weak persons cannot stand 

 much loss of blood. Women can stand loss of blood better than men. 



The quantity of blood may be considerably increased by the injection 

 of blood from the same species of animal (PANUM, LANDOIS, WORM 

 MULLER, PONFICK). According to WORM MULLER the normal quantity 

 of blood may indeed be increased as much as 83 per cent without pro- 

 ducing any abnormal conditions or lasting high blood -pressure. An 

 increase of 150 per cent in the quantity of blood may, with a considerable 

 variation in the blood-pressure, be directly dangerous to life (WoRM 

 MULLER). If the quantity of blood of an animal is increased by trans- 

 fusion with blood of the same kind of animal, an abundant formation 

 of lymph takes place. The water in excess is eliminated by the urine; 

 and as the protein of the blood-serum is quickly decomposed, while the 

 red blood-corpuscles are destroyed much more slowly (TSCHIRJEW, FORS- 

 TER, PANUM, WORM MULLER 5 ), a polycythsemia is gradually produced. 



1 Journ. of Physiol., 25. 



2 Deutsch. Arch. f. klin. Med., 93 (1908). 



3 Virchow's Arch., 29. 



4 Transfusion und Plethora, Christiania, 1875. 



5 Panum, Nord. med. Ark., 7; Virchow's Arch., 63; Landois, Centralbl. f. d. med. 



