82 ORGANISED FLUIDS. 



and by its admixture, according to Henle, with distilled 

 water. 



Sulphuric acid, and other acids which are agitated with 

 the blood, change its colour from red to blackish brown. 



The nitrous and nitric oxides cause vermilion blood to take 

 a deep purple tint.* 



The power possessed by thT)se substances which brighten 

 the colour of dark venous blood is supposed to be derived 

 from the oxygen which they contain, and by means of which 

 a chemical transformation in the condition of the red element 

 of the blood, the hematine, is effected, a portion of oxygen 

 being absorbed during the change of colour. Those sub- 

 stances, however, which cause arterial blood to assume the 

 tint of venous blood are presumed to exert their influence 

 by means of the carbon of which they are compounded, and 

 a portion of which becomes imbibed during the work of 

 transmutation. 



Henle, nevertheless, considers that these several alterations 

 of colour arise rather from mechanical than chemical causes, 

 and that they depend upon the state of aggregation of the 

 particles of the colouring matter, these being differently dis- 

 posed according to the nature of the reagent employed. 



Thus Henle remarks |, "It is evident that the colour of 

 the blood is brightened under the influence of substances 

 which oppose the dissolution of the hematine in the serum 

 and maintain or re-establish the flat form of the corpuscles, 

 as the concentrated solutions of salts and of sugar, while pure 

 water, which dissolves the colouring matter and causes the 

 corpuscles to swell, deepens the colour of the blood." 



Hamburger {, according to Henle, has even observed that 

 weak solutions of the chlorides render the colour of the blood 

 deeper, while their concentrated solutions make it pass to 

 vermilion. 



Again, according to the observations of Schultz, it would 

 appear that the red blood corpuscles are flattened by the 



* Henle, Anatomic Generale, tome premier, page 471. 



f Loc. cit. page 471. 



J Hamburger, Exp. circa Sauguinis Coagulationem, pp. 32. 42. 



