THE INDIVIDUAL GROUPS OF PROTEINS 473 



It is most readily determined with fair accuracy by Hammerschlag's 

 method. A mixture of chloroform and benzene or ligroin of specific 

 gravity about 1055 is prepared. A drop of blood is blown out from a 

 capillary tube below the surface of the mixture ; it assumes a spherical 

 shape and will float or sink. Benzene or chloroform is added until the 

 mixture is such that the drop neither sinks nor rises. The specific 

 gravity of the mixture is ascertained* by means of a hydrometer or by 

 means of specific gravity beads. It is the same as that of the blood. 



The specific gravity may also be determined by Roy and Lloyd-Jones' 

 method. A series of solutions of sodium sulphate of specific gravity from 

 1035-1070 are prepared. Portions of these solutions are placed in glass 

 thimbles or small test tubes. The blood from the finger (or defibrinated 

 blood) is drawn up into a capillary pipette which is made from* a glass 

 tube and bent at right angles ; the pipette is conveniently furnished with 

 an india-rubber cap. A drop of blood is ejected from the pipette in 

 the centre of one of these solutions. It rises or sinks ; drops are ejected 

 into neighbouring solutions. In one of them it will remain stationary. 

 The specific gravity of this solution will be the same as that of the 

 blood. 



(3) The Red Blood Corpuscles. 



The number of red blood corpuscles in the blood of animals varies 

 in health considerably, thus it is roughly : 

 In man 5,000,000 

 dog 6,500,000 

 cat 9,000,000 

 pig 6,000,000-8,000,000 



horse 7,700,000 Hn l cubic millimetre - 



ox 6,000,000-8,000,000 

 sheep 10,000,000 

 goat 1 3, 000,000- 1 8, ooo, oooJ 



Variations in the number of corpuscles occur in man when he lives 

 at different altitudes, more corpuscles being present at high altitudes. 

 Variations in the number also occur pathologically. A variation of 

 100,000 in 5,000,000 is of no physiological importance. 



Dogs' red corpuscles have the following composition (Abder- 

 halden) : 



Water 64-4 per cent. Haemoglobin 3275 per cent. 



Solids 35-6 Proteins 9-92 



