316 THE BLOOD 



the orientated surface layers, by removal of plasma or by disturb- 

 ance of the K/Ca ratio, leads at once to altered permeability and 

 an alteration in shape. From such experiments one infers that 

 the corpuscular capsule in contact with plasma is not of uniform 

 elasticity. This lack of uniformity is abolished when the cell is 

 completely removed from plasma or serum. 



The conclusion at present drawn from experiments mentioned 

 in this chapter, viz. conductivity of whole blood compared with 

 that of laked blood, haemolysis in general, and, finally, the colliga- 

 tive properties of blood and plasma about to be considered, is that 

 the red corpuscle is a bag containing fluid and no spongework or 

 stroma. In other words, the continuous phase of the corpuscular 

 contents is water + crystalloids + cell globulin ^, while the disperse 

 phase is haemoglobin with some " bound " water and possibly 

 adsorbed crystalloids. The blood as a whole, then, consists of a 

 water-in-colloid complex in which is suspended small encapsulated 

 drops of a colloid-in- water complex. These two systems may be 

 compared in their properties to a series of little gelatin + collodion 

 bags filled with phenol-dispersed-in-water, suspended in a fluid, 

 water-in-phenol. 



Contents of erythrocyte. The nature and volume of the disperse 

 phase in the contents of the corpuscle is of considerable academic 

 interest. The next chapter will be devoted almost entirely to the 

 study of the function of the haemoglobin, which is the main 

 constituent of the disperse phase wdthin the cell. It is a conjugated 

 protein composed of about 94 per cent, of a colourless protein — 

 globin — belonging to the histone group, and 6 per cent, of a 

 brownish ferro-porphyrin called haem. Haem is completely 

 insoluble in water at a jjH of about 7 and less, i.e. in neutral 

 and acid aqueous solutions, but dissolves in the presence of alkali. 

 Such a solution gives a diffuse absorption spectrum in the yellow 

 region not at all like that characteristic of haemoglobin. On 

 combining with globin, however, the spectrimi of reduced alkaline 

 haematin (haemochromogen) is obtainable from the compound. 

 Probably four haemochromogen molecules (mol. wt. about 17,000) 

 polymerise under the influence of an increase in the H+ ion con- 

 centration to form one haemoglobin molecule (mol. w't. about 

 68,000). The pigment is dispersed in gel form through a sol 

 within the membrane of the corpuscle. Actually about 32 grams 

 of Hb and 63 grams of water are found in every 100 grams of red 

 cells, while only 18 grams of Hb can be dissolved in 100 grams of 

 water. 



Various estimates have been made of the volume of the dispersed 

 phase relative to the volume of the continuous phase. A know- 



