THE BLOOD. 485 



colour entirely vitiated the indications of both litmus and turmeric; and 

 even the serum obtained after contraction of the clot was too much 

 tinged to admit of the satisfactory application of the test paper. 



" Being thus baffled in my experiments with the sheep, I had recourse 

 to the horse, in which the red corpuscles subside with peculiar rapidity 

 in the plasma, giving rise to the buffy coat well known to occur in the 

 blood of that animal in the state of health, so that the opportunity would 

 be presented of obtaining liquor sanguinis free from red corpuscles, to 

 which the tests could be applied without risk of fallacy. Accordingly, 

 yesterday afternoon, a horse having been placed at my disposal by my 

 friend Mr Gamgee of the New Veterinary College, I tied into the right 

 jugular vein one end of a piece of vulcanized India rubber tube, four 

 yards in length, the greater part of which was coiled up in a freezing 

 mixture, and some of the blood, having been allowed to remain for a 

 while in the tube, was shed into vessels standing in ice-cold water. 

 Its temperature on first escaping into the air was 39^ Fahr., and hav- 

 ing been since kept in the cold it is still only partially coagulated at the 

 present time (twenty-nine hours after it was shed). At first, however, 

 it appeared as if we were likely to fail, the blood of this horse being a 

 rare exception to the general rule, in exhibiting for a long time no ap- 

 pearance of the 'sizy' layer. But after it had stood for about two 

 hours, I succeeded in removing from the surface, by means of a glass 

 tube, a sufficient amount of liquor sanguinis for the performance of an 

 experiment, taking care that the glass into which it was shed, 

 and the tube, were both near the freezing point. To half a drachm of 

 this plasma I now added one minim and a half of moderately dilute 

 acetic acid, which had the effect of rendering it distinctly acid, as in- 

 dicated by its communicating a red tint to litmus and restoring the 

 colour of turmeric paper which had been reddened by dipping it in the 

 portion of the liquor sanguinis which had not been acidulated. I kept 

 the specimen in ice-cold water till this evening. For a long time it re- 

 mained perfectly fluid, except the formation of little soft coagulum 

 at the surface, just as in the unacidulated blood ; but a few drops 

 placed in a watch-glass and brought into a warmer atmosphere, coagul- 

 ated in about the same time as the blood that first flowed from the tube, 

 a soft clot forming in about a quarter of an hour. Even at the expira- 

 tion of twenty-four hours a portion of what remained in the cold was 

 still fluid, though faintly acid, but set into a pretty firm clot on being 

 removed into a wanner situation. 



