84 ORGANISED FLUIDS. 



to account for the very remarkable alterations of colour to 

 which the vital fluid is subject. 



The changes of colour of dark blood to a vermilion 

 hue, and of this again to the deep tint of venous blood, 

 admit of a chemical explanation being given, the essential 

 element of the former change being oxygen gas, and of the 

 latter carbonic acid gas. Thus, even the remarkable effect 

 of the application of the chlorides may be accounted for by 

 reference to the well-known operation of chlorine as a bleach- 

 ing agent, viz. through the power which it possesses of 

 depriving water of its hydrogen, and altering the state of 

 combination of the oxygen. 



With respect to the observations of Schultz on the effect 

 of carbonic acid and of oxygen in altering the form of the 

 red blood corpuscles, and on which fact the entire of Henle's 

 theory rests, I would observe that, in conjunction with Mr. 

 Miller, the gentleman who manifests so much of patience, 

 skill, and intelligence in the execution of the drawings of 

 this work, and who is moreover an excellent chemist, I have 

 made many experiments with the view of ascertaining the 

 power possessed by the former reagent in modifying the 

 form of the elliptical corpuscles of the blood of the frog, the 

 blood being in some cases submitted to the direct action of 

 the gas, and in others the animal itself being subjected to 

 its influence. 



The result of these experiments, on my mind, is the con- 

 viction that the effect of this gas on the figure of the 

 corpuscle is not appreciable. I am therefore disposed to 

 allow but little weight to the mechanical theory of the changes 

 of colour experienced by the blood. 



Venous blood does not present precisely the same tint of 

 colour or the same characters in all parts' of the system : thus 

 the blood found in the vena porta is deeper in colour than 

 any other venous blood, and, according to Schultz, it does not 

 redden either on the application of oxygen gas or of salts, 

 and does not coagulate, or gives but a divided clot ; it is 

 richer in water, in cruor, and in fat, and poorer in albumen, 

 than ordinary venous blood. 



