CHAPTER XV 

 BLOOD AND LYMPH 



BLOOD is composed of four types of form-elements (erythrocytes or 

 red blood corpuscles, leucocytes or white blood corpuscles, blood plates 

 or plaques and blood dust or hemoconein) held in suspension in a fluid 

 called blood plasma. These form-elements compose about 60 per cent of 

 the blood, by weight. Ordinarily blood is a dark red opaque fluid due to 

 the presence of the red blood corpuscles, but through the action of 

 certain substances, such as water, ether, or chloroform, it may be 

 rendered transparent. Blood so altered was formerly said to be laked. 

 The term hemolysis is now used in this connection and substances which 

 cause such action are spoken of as hemolytic agents. The hemolytic 

 process is simply a liberation of the hemoglobin from the stroma of 

 the red blood corpuscle. Normal blood is alkaline in reaction to 

 litmus, the alkalinity being due principally to sodium carbonate. 

 When examined according to physico-chemical methods the blood is 

 found to be very faintly alkaline (P H = 7-35)- In other words it 

 has a hydrogen ion concentration less than that of water. Even in 

 cases of the most pronounced acidosis the reaction of the blood is 

 but slightly altered (see Chapter XVII). The specific gravity of the 

 blood of adults ordinarily varies between 1.045 an d i-75- It varies 

 somewhat with the sex, the blood of males having a rather higher 

 specific gravity than that of females of the same species. Under 

 pathological conditions also the density of the blood may be very greatly 

 altered. The freezing-point (A) of normal blood is about o.56C. 

 Variations between 0.51 and o.62C. maybe due entirely to dietary 

 conditions, but if any marked variation is noted it can in most cases 

 be traced to a disordered kidney function. The total amount of blood 

 in the body has been variously estimated at from one-twelfth to one- 

 fourteenth of the body weight. Perhaps 1/13.5 is the most satisfactory 

 figure. Abderhalden and Schmidt 1 have suggested a unique method 

 for the determination of this value. It is based upon the change in 

 the optical activity of the blood upon injection of a body of known 

 optical activity, such, for example, as dextrin. Keith, Rowntree and 

 Geraghty 2 have recently made use of a dye in the determination of 

 blood volume. 



Among the most important constituents of blood plasma are the four 



Abderhalden and Schmidt: Zeit. physiol. chem., 66, 120, 1910. 

 Keith, Rowntree and Geraghty: Arch. Int. Med., 16, 509, 1915. 



248 



