CH. X.] HAEMOLYSIS. 239 



acids, alkalies, soaps and " saponins " cause the blood to be 

 laked. Some of these act by dissolving the lipoids of the 

 envelope and stroma ; others possibly act on the proteins. 



If the washed corpuscles be suspended in normal 

 saline containing various buffer solutions, it will be found 

 that haemolysis takes place in all solutions acid to PH=S*I. 



Lecithin and cholesterol seem to be somewhat antagon- 

 istic in respect to haemolysis, the former accelerating and 

 the latter inhibiting the phenomenon. 



Certain pathogenic organisms produce specific hae- 

 molysins, notably the tetanus bacillus. The poisonous 

 action of some snake venoms is in part due to the rapid 

 destruction of the red corpuscles. 



Haemolysis is brought about by the absorption into 

 the system of a large number of chemical substances, e.g. 

 arsine, pyrogallol, toluylenediamine. 



Another method of inducing haemolysis is by the 

 addition of certain organic substances developed in certain 

 animals. Thus rabbit's corpuscles that have been washed 

 with isotonic saline are laked when treated with the 

 blood serum of a dog. This haemolytic power of dog's 

 serum on rabbit's blood is very much increased by previously 

 injecting the dog with rabbit's blood'. 



283. Have two burettes, one containing i per cent, sodium 

 chloride, the other distilled water. 



Label a series of clean, dry test-tubes A, B, C, etc. 



In A place 4-5 cc. NaCl and 5-5 cc. H 2 O - -45 % NaCl. 

 " 5 > 5 ~ "5 



C 5*5 4'5 = -55 



D 6 4 = -6 



E 6-5 3-5 = -65 



F 7 .. 3 = 7 



To each tube add three drops of fresh defribinated blood, 



