486 VETERINARY PHYSIOLOGY 



endosmosis, the capsule bursts, and the pigment escapes. 

 Erythrocytes may therefore be used as a means of determin- 

 ing the osmotic equivalent — the molecular concentration — 

 of a fluid. 



27id. By the action of substances which dissolve the 

 lipoids of the stroma, e.g. salts of the bile acids (see p. 324), 

 chloroform, ether, etc. 



ord. By Hsemolysins. («) The serum of each species of 

 animal contains a substance, destroyed by heating to 5 5' C, 

 which is hsemolytic to the blood of animals of other species, 

 e.g. the serum of eels' blood contains a powerful haBmolysin 

 for rabbits' erythrocytes, and the serum of the dog a less 

 powerful one. (b) Further, by injecting the blood or the 

 erythrocytes of one species of animal into another species, a 

 hsemolysin is developed which has a specific action on the 

 erythrocytes of the first species (p. 614). 



Mh. By killing the erythrocytes in the body by inject- 

 ing substances which poison them, such as phenylhydrazin. 

 They are subsequently disintegrated and their pigment 

 removed. This, of course, is not a true hiaemolysis. 



5. Chemistry. — (1) The stroma of the erythrocytes which 

 is left after the pigment is washed out is a sponge work 

 made up of a globulin-like substance, in which lipoids, 

 such as cholesterol and lecithin, occur in considerable 

 quantities, and seem to form a capsule or cell membrane. 

 Potassium is the base most abundantly present in man. 



(2) Haemoglobin. — The pigment is Haemoglobin. It con- 

 stitutes no less than 90 per cent, of the solids of the 

 erythrocytes. In many animals, e.g. the rat, when dissolved 

 from the corpuscles, it crystallises very readily {Chemical 

 Physiology). The crystals prepared from human blood 

 are rhombic plates. When exposed to air they are of a 

 bright red colour, but if placed in the receiver of an air- 

 pump at the ordinary temperature they become of a purplish 

 tint. The same thing occurs if the haemoglobin is in 

 solution, or if it is still in the corpuscles. The addition of 

 any reducing agent such as ammonium sulphide or a ferrous 



