THE BLOOD CELL 97 



of clinical medicine. The hemolytic serum produced by the injection 

 of foreign corpuscles owes its activity to two substances. The one 

 called the amboceptor, or immune body, is specific against the type 

 of cell injected and is increased during immunization. The second 

 body is the complement; it is nonspecific, and is not increased dur- 

 ing immunization. Complement is destroyed by heating the serum for 

 one hour at 55 C., leaving the amboceptor alone present. Corpuscles 

 placed in such serum are not hemolyzed until complement either from 

 fresh immune or from nonimmune serum is added. 



The serum of animals possessing natural hemolytic properties towards 

 the corpuscles of other animals likewise owes its effect to the joint action 

 of amboceptors and complement. 



Ordinarily the serum from animals of one species does not exhibit 

 hemolytic properties to blood from another animal of the same species. 

 In unusual cases, however, the serum of an animal will produce hemol- 

 ysis of the corpuscles of an animal of the same species. Such sera are 

 said to possess isohemolysins. The fact is of great importance in the 

 transfusion of blood from one individual to another. 



The cause of the acute hemolysis which occurs in the disease parox- 

 ysmal hemoglobinuria is not known. It is probably due to the presence 

 of a hemolytic substance which unites with the blood corpuscles at 

 temperatures below the normal body temperature, since the attack fol- 

 lows exposure to cold, and blood from patients subject to the condition 

 may be hemolyzed in vitro by cooling and subsequently heating it. 



LEUCOCYTES 



There are a number of varieties of white cells in the blood. These are 

 differentiated from one another by their shape, staining properties, and 

 the granules in their protoplasm. We may divide them into two main 

 groups nongranular mononuclear cells and granular polynuclear cells. 



The nongranular mononuclear cells are termed lymphocytes. Two va- 

 rieties are differentiated, the small and the large. 



The small mononuclear leucocyte makes up from 23 to 28 per cent 

 of the total leucocytes and the large mononuclear, from 2 to 4 per cent. 



The polynuclear leucocytes are divided into three groups according 

 to whether their granules stain with basic, neutral or acid stains. The 

 leucocytes that stain with basic dyes, or the basophile cells, are very 

 few, making up less than one per cent of the total count. Likewise the 

 acid-staining granular cells, acidophile, are few, comprising from 2 to 

 4 per cent of the total count. The most numerous are the neutrophiles, 



