106 PHYSIOLOGY < IIAI-. 



certain value, forming oxy haemoglobin, which with a fall of tlie 

 partial pressure is again reduced to haemoglobin. It prevails in 

 the form of oxyhaemoglobin in arterial, as haemoglobin and 

 oxyhaemoglobin in venous, exclusively as haemoglobin in asphyxial 

 blood. 



There are many physical and chemical means by which the 

 pigment is easily separated from the stroma of the corpuscles and 

 dissolved in the plasma. Among the physical methods are 

 warming of the blood to 50-60 C., repeated freezing and thawing, 

 the discharges of a Leyden jar, induced or galvanic currents ; 

 among the chemical methods, simple dilution with water, addition 

 of ether, chloroform, dilute alcohol, acid or alkaline solutions, bile, 

 heterogeneous serum, etc. By using sodium chloride solutions of 

 various concentrations, different degrees of diffusibility of pigment 

 can be detected in different corpuscles and different individuals. 



According to Winter's researches (1890), the isotonic solution, 

 i.e. that which has the same degree of molecular concentration as 

 the corpuscles (and therefore produces no disturbance of osmotic 

 relations and no diffusion of haemoglobin in the plasma), is repre- 

 sented by a solution of about 0'91 per cent NaCl in distilled 

 water. 



In proportion as the pigment separates out from the stroma, 

 the corpuscles grow pale, and finally change into roundish, 

 colourless, almost transparent bodies which have been termed 

 ghosts (Blutschatteri), because they are almost invisible. They 

 stain brown with iodine and can thus be detected. 



In order to study the chemical composition of the stroma of 

 the erythrocytes a large mass of blood corpuscles must be collected, 

 separated from the plasma, washed with dilute solution of sodium 

 chloride, and completely freed from haemogloblin by the addition 

 of 5-6 volumes of distilled water. By this treatment all is 

 removed save the stroma, which forms a gelatinous mass and can 

 be separated by filtration from the watery solution. 



The small amount of matter remaining on the filter dissolves 

 in dilute salt solution, and gives all the reactions of globulin. 

 But the stromata separated from the erythrocytes of birds contain, 

 in addition to globulin, a considerable quantity of nuclein, derived 

 from the nuclei of these corpuscles (Flosz, Hoppe-Seyler). Kossel, 

 with dilute hydrochloric acid, also extracted a substance belonging 

 to the albumose group, to which he gave the name of histone. 



If further chemical researches prove that the erythrocytes 

 of mammals contain no nuclein, this would be an additional 

 proof that they really are non-nucleated, which has been denied 

 by some observers. 



An ethereal extract of a mass of stromata yields the other 

 organic components of protoplasm, lecithin and cholesterin. 



The inorganic substances of the stroma consist of potassium 



