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 hemolylic 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 neutral, i.e., it does not contain an excess of hydroxyl 

 ions. Even in cases of the most pronounced acidosis the reaction of the 

 blood is but slightly altered. The specific gravity of the blood of adults 

 ordinarily varies between 1.045 an d I-O75- 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. may be 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. Abder- 

 halden and Schmidt 1 have suggested a unique method for the deter- 

 mination 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 



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



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



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