Dr John Davy on the Blood. 



21 



was added to the blood, its coagulation was not prevented. 

 These results, all of them well marked, seemed to warrant 

 the conclusion that the volatile alkali is no wise concerned 

 in the coagulation of the blood. I have made many experi- 

 ments since, and they have all been of a confirmatory kind.* 



The other question, whether the volatile alkali is a normal 

 constituent of the blood, is not so easily answered, and there 

 is a difference of opinion on the subject among physiologists : 

 thus, Frederichs, who has the reputation of being an ac- 

 curate observer, thinks that it forms no part of the vital 

 fluid ; whilst Dr Hammond takes the opposite view, and 

 believes with Dr Kichardson that it is an integrant part of 

 that fluid, and that he has detected it in no less than four- 

 teen experiments, even in the blood of the common fowl, 

 employing Dr Eichardson's test — that is, a slip of glass 

 moistened with hydrochloric acid, and exposed to the vapour 

 rising from the blood. f 



He does not state the particulars of the trials he made. 

 This, I cannot but hold to be an omission, considering the 

 nature of the fluid, how readily it changes, how apt it is to 

 undergo decomposition, — that of the putrid kind, — and in 

 the act to give rise to the production of ammonia in the form 

 of the volatile carbonate. 1 believe there is no exaggeration 

 in stating that the instant the blood is taken from the living 

 body a change of this kind commences ; hardly perceptible 

 indeed at first, but with advance of time, especially at a 

 temperature above 60 Fahr., rapidly increasing. In illustra- 

 tion, I shall give the details of an experiment which I have 

 made after the reading of Dr Hammond's statement. 



When the thermometer in the open air was 62°, a pullet 

 was killed by dividing the great vessels in the neck. The 

 blood, which was very florid, was collected in three small 

 cups, and each was covered with a plate of glass moistened 

 with hydrochloric acid. In each the blood coagulated in 

 less than two minutes. After an exposure of five minutes 

 the glass from one of them was removed, and the acid 



* See Trans. Eoy. Soc. of Edin. for 1859 ; and my Physiological Ke- 

 searches, London, 1863. 



t Physiological Memoirs, Philadelphia, 1863. I quote this author, being 

 one of the latest and ablest inquirers I can refer to. 



