586 



[June 11, 



Fig. 2. 



that the blood, in slipping through this cylindrical tube, had had 

 little opportunity of being influenced by its walls. The portion of 

 the blood that came first in contact with the walls of the tube had 

 coagulated; and it is to be observed that I never found, in these 

 experiments, the blood altogether fluid, even after a comparatively 

 short time : there has always been a certain amount of coagulation, 

 and only a certain amount of fluidity. A layer of blood having thus 

 coagulated upon the internal surface of the tube, the fresh blood 

 which continued to flow through it, was not brought "into contact 

 with the walls of the tube at all, but with their lining of coagulated 

 blood. 



It has been long known that if blood is stirred with a rod, the 

 process of coagulation is pro- 

 moted. It seemed desirable to 

 ascertain distinctly whether the 

 cause of this was the contact of 

 the foreign solid, or the oppor- 

 tunity given for the escape of 

 ammonia; for it is quite true 

 that, in the ordinary process of 

 stirring blood, more or less air 

 is mixed with it. For the pur- 

 pose of determining this I de- 

 vised a somewhat complicated 

 experiment, which, however, it 

 may be worth while to men- 

 tion. I made an apparatus 

 (fig. 2) of two portions of glass 

 tube, A and B, connected in a 

 vertical position by means of 

 vulcanized india-rubber, I, the 

 lower portion of the glass tube 

 being also connected by india- 

 rubber, I', with a wooden han- 

 dle, which handle, H, was pro- 

 vided with an upright piece of 

 wire, from which spokes pro- 

 jected in different directions, so 



