THE BLOOD. 115 



rate, metahaemoglobin is observed in human and in canine blood 

 (MARCHAXD and KAHN ) ; but, on the contrary, no formation of 

 metahaemoglobin takes place in the blood of rabbits (STOKVIS and 

 KIMMYSER). A formation of metahaemoglobin may be caused at 

 the expense of the haemoglobin by the inhalation of amyl nitrite, 

 as also by the action of a number of other medicinal bodies (HAYEM 

 and others). 



The quantity of blood is indeed somewhat variable in different 

 species of animals and in different conditions of the body; in gen- 

 eral we consider the entire quantity of blood in adults as about 

 iV~iV ^ the weight of the body, and in new-born infants about 

 T ^. 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), and it may therefore be also pro- 

 portionally greater in starving individuals than in well-fed ones. 



By careful bleeding the quantity of blood may be considerably 

 diminished without any dangerous symptoms. The loss of blood 

 to J of the normal quantity has as sequence no durable sinking of 

 the blood-pressure in the arteries; while the smaller arteries ac- 

 commodate themselves to the small quantities of blood by contract- 

 ing (WORM MULLER). A loss of blood to \ of the quantity reduces 

 the blood-pressure considerably, and a loss of of the blood in 

 adults is dangerous to life. The faster the bleeding the more dan- 

 gerous 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 in- 

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

 WORM MULLER, PONFICK). According to WORM MULLER, the nor- 

 mal quantity of blood may indeed be increased to 83$ without pro- 

 ducing any abnormal conditions or continuing high blood-pressure. 

 An increase of the quantity of blood to 150$ may be directly dan- 

 gerous to life (WORM MULLER). If the quantity of blood of an 

 animal is increased by transfusion 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 albumin of the blood 

 serum is quickly decomposed, while the red blood-corpuscles are 



