ICO THE BLOOD. 



kept fluid by preventing the escape of volatile substances, 

 and the vapor of coagulating blood forced through another 

 specimen of blood prevents coagulation so long as it continues 

 to pass, something is given off from the blood which, when 

 contained in this fluid, has the power of retaining fibrin in 

 its fluid state. Having gone thus far in the investigation, 

 the next point is to subject the vapor of blood to analysis, 

 and ascertain, if possible, what substance or substances it 

 contains which, When retained in the blood, or introduced, 

 have the power of keeping it fluid. 



This was the next step in .Richardson's investigations. 

 He found that blood-vapor contained, among other things, 

 ammonia. This he detected by passing blood-vapor through 

 hydrochloric acid and afterwards testing it with the per- 

 chloride of platinum, forming the ammonio-chloride of plati- 

 num. He also obtained crystals of the chloride of ammo- 

 nium, by allowing the vapor to pass over a glass slide moist- 

 ened with hydrochloric acid. He demonstrated in this way 

 the presence of ammonia in the exhalation from the blood of 

 the human subject, as well as the inferior animals. He also 

 demonstrated by numerous experiments that ammonia mixed 

 with blood, or the vapor passed through it, will prevent coag- 

 ulation ; while the passage of air and the various gases has 

 the effect of hastening, rather than retarding this process. 

 It was further demonstrated that ammonia is constantly dis- 

 charged by the organism, particularly by the lungs ; and, of 

 course, must be as constantly produced in the tissues, and 

 taken up by the blood in the course of the circulation. 1 



The points above enumerated certainly seem to be ex- 



1 In the discussion of Richardson's views, we have attempted to connect the 

 great experimental links in his chain of evidence. His admirable and laborious 

 treatise contains details of 399 experiments; and though a summary is given at 

 the end of each chapter, and a summary at the conclusion, much labor is necessary 

 on the part of the reader to separate those which are important from the great 

 mass of minor facts, and appreciate the proofs of the doctrines advanced. This, 

 as it seems to me, has had the effect of causing the views of Dr. Richardson to 

 receive far less attention at the hands of physiologists than they really merit. 



