BODY TISSUES AND FLUIDS 427 



able value. In the first place, the solid content of the blood is a very 

 excellent index of the functional condition of the blood, blood proteins and 

 blood cells taken together, and furthermore is of value in explaining small 

 fluctuations in the content of the individual constituents. Normally the 

 total solids amount to from 19 to 23 per cent, although in primary and sec- 

 ondary anemia, severe nephritis, etc., the amount may be decreased to 

 nearly one-half these figures. That the total solids may be increased in 

 cholera, as a result of the severe diarrhea, was recognized by Carl Schmidt 

 many years ago. An increase in the blood solids was found by Underbill 

 to result from poisoning by the lethal war gases. 



Specific Gravity. The specific gravity of human blood in the adult 

 male varies between 1.041 and 1.067, the average being about 1.055. For 

 the female the figures are slightly lower. The specific gravity obviously 

 varies in much the same way as the solids. The determination appears 

 to be little used at the present time. Gettler and Baker have recently 

 given some new observations on serum. They found the specific gravity 

 of the serum of both men and women to range from 1.026 to 1.030, the 

 majority being between 1.027 and 1.029. 



Reaction and Hydrogen Ion Concentration. Normal human blood as 

 it exists in the body is faintly alkaline in reaction, i. e., it has a hydrogen 

 ion concentration only slightly less than pure water, and this degree of 

 alkalinity tends to be very constantly maintained under a variety of con- 

 ditions. The blood itself, owing chiefly to the "buffer" action of the car- 

 bonates of the plasma and phosphates of the corpuscles, can take up con- 

 siderable amounts of acid or alkali without much change in its reaction. 

 An appreciable change in its hydrogen ion concentration indicates a failure 

 of this protective mechanism and the presence of a severe acidosis. From 

 a practical point of view the CO 2 combining power of the blood is much 

 more useful, since the change occurs much earlier (see below). 



As the result of a series of analyses on thirty normal individuals by 

 the gas chain method, as described by Michaelis, Gettler and Baker found 

 pH to range from 7.52 to 7.60 at 22C. Levy, Eowntree and Marriott 

 have described a very simple indicator method of determining the hydro- 

 gen ion concentration and serum. With this method oxalated blood from 

 normal individuals gave a dialysate with a pH varying from 7.4 to 7.6, 

 while that of the serum ranged from 7.6 to 7.8. In a small series of 

 clinical acidoses, the serums varied from 7.55 to 7.2 and the oxalated blood 

 from 7.3 to 7.1. 



Blood Proteins. Considerable experimental evidence has recently been 

 adduced by Kerr, Hurwitz and Whipple (c) which points to the liver as be- 

 ing concerned in the maintenance of a normal level of the blood serum 

 proteins (albumin and globulin). The evidence is not so convincing nor 

 so striking as that obtained by Whipple for the plasma protein fibrinogen 

 which has such an intimate relation to liver injury. In the case of the 



