I 5 8 



ESSENTIALS OF PHYSIOLOGY. 



Serum which is either naturally or artificially hsemolytic loses its 

 power to dissolve red corpuscles if it is heated to 55 C. But such 

 serum can have its hsemolytic power restored by the addition of serum 

 from a normal animal. The hsemolytic power of any serum therefore 

 depends upon the presence of two substances, one which is present in 

 normal serum and is destroyed at a temperature of 55 C., and is usually 

 called complement', and a second which is stable at 55 C., and may be 

 produced in an animal by injection of the corpuscles of another animal. 



Haemoglobin may thus be set free from the erythrocytes and pass 

 into solution in the surrounding fluid in three ways : 



(1) By a physical process, as by dilution with water or by alternate 



freezing and thawing. 



(2) By chemical means, for example, the solution of the lipoid 



stroma of the corpuscles by bile salts, amyl alcohol, soaps, or 

 other reagents. 



(3) By physiological agents, called haemolysins, the exact mode of 



action of which is not known. 



As the result of haemolysis by any of these methods the blood is 

 said to be "laked." The haemoglobin is in solution, and the blood, 

 previously opaque on account of the reflection of light from the 

 erythrocytes, becomes transparent. 



THE CHEMICAL COMPOSITION OF RED BLOOD CORPUSCLES. 



The red corpuscles may be ob- 

 tained in sufficient quantity for 

 analysis by centrifugalising blood 

 and washing the deposit with *9 

 per cent. NaCl. They are found to 

 consist of 63'3 per cent, of water 

 and 36*7 per cent, of solids. Haemo- 

 globin forms 95 per cent, of the 

 dry solids, the remainder being 

 made up of nucleoprotein, lecithin, 

 cholesterol, fatty acid, and inorganic 

 salts, the most abundant of the 

 latter being potassium phosphate. 

 The stroma is, therefore, as has 

 already been pointed out, largely 

 of a lipoid nature. 



Haemoglobin is a compound of 

 ^^ ^.^ is & protein belong . 



hki r r, the gl "" ea - ing to the group of histones, with an 



FIG. 50. Hfemoglobin crystals, mag- 

 niBed. (From Qoain's 



