170 The Microscope. 



gouty and rheumatic people is prone to decomposition ; for it is a 

 well known law that the action of any acid upon the blood, with the 

 single exception of carbonic acid, destroys its integrity, and 

 especially its haemoglobin. We have already mentioned that in the 

 living body hcemoglobin is joined to a potassium carbonate. If 

 even a large quantity of an aqueous solution of carbonate of potassa 

 is mixed with a solution of hsemato-crystalline, we obtain a clear, 

 transparent mixture without turpidity, change of color, and without 

 modifying the spectral bands. 



Considerations of this kind allow us an insight into the inner- 

 most recesses of blood life, and we at once understand how it comes 

 that carbonic acid is so amply present in arterial blood, in spite of 

 the oxydizing power of a superabundant quantity of oxygen present. 



The individual acts of respiration are of too short duration to 

 make the expulsion of the entire volume of carbonic acid a matter 

 of possibility. A certain given quantity will, therefore, at all times 

 remain unexpired. 



At first sight, this would seem highly dangerous to life, but 

 nature has made ample provision to avert this supposed danger, and 

 to apply this surplus to some wise purpose in the economy. She 

 assigns to this irrespirable gas the important task to assist in the 

 conservation of the haemoglobin, by employing it to form potassa 

 carbonate, for which said haemoglobin has so strong an affinity, using 

 the resulting free oxygen for purposes of oxidation, and by this 

 interesting exchange or metabolism, restoring the normal status of 

 haemoglobin. 



Certain morbid conditions favor a disposition of the haemoglo- 

 bin of the blood to crystallize in mass, either directly after the death 

 of the animal, or when blood is abstracted during life. In this 

 direction we have Brown Sequard's highly interesting observations. 

 He states that after ablation, or extirpation of the suprarenal capsrdes 

 of animals, the blood of said animals, either shortly before their 

 death or directly after it, showed an irresistible tendency to crystal- 

 lize spontaneously, so that one drop placed before the microscope 

 would cover the entire field of vision with a network of ciystals, 

 like numberless fine needles crossing each other. 



What bearing may these observations have upon Addison's 

 disease, being a disease of the supra renal capsules ? The peculiar 

 bronzed color of the skin may possibly depend upon an alteration of 

 the blood coloring matter; for in one case under my own observation 

 and treatment, of Addison's disease, associated with bloody urine, 



