594 [June 11, 



orifice should be in the current of the main trunk of the vein, tied it 

 in securely. I then removed the cork and made pressure on the vein 

 at the cardiac side, causing the vessel to swell and blood to pass into 

 the fine part of the tube ; and before the blood had reached the part 

 of the glass moistened by the ammonia, I put in the cork again and 

 withdrew the tube. In a short time, on introducing a hook of fine wire 

 into the extremity of the tube, I found the blood already coagulated ; 

 but on filing off a small portion of the tube, I found the blood there 

 fluid. The portion of blood thus exposed soon coagulated, when, a 

 second small piece of the tube being removed by the file, fluid blood 

 was again disclosed, which again soon coagulated; and this pro- 

 ceeding was repeated with the same results time after time, till, near 

 the thick part of the tube, the ammonia in the blood was so strong 

 as to prevent coagulation altogether. 



This experiment illustrates how fitted the ammonia is to maintain 

 the fluidity of blood, and also how apt it is, when present in the 

 blood, to fly speedily off from it, leaving it unimpaired in its coagu- 

 lating properties ; and it must be confessed that the end of the tube 

 sealed with a small clot resembled most deceptively the extremity of 

 a divided artery similarly closed. But although the experiment 

 seems in so far to favour the ammonia theory, it will tell differently 

 when I mention the object with which it was performed. It appeared 

 to me that, if the cause of the fluidity of the blood was free ammonia, 

 then, if I provided an ammoniacal atmosphere in the tube, and intro- 

 duced blood by pressure directly from the vein into this ammoniacal 

 atmosphere, this blood, lying between the strong ammoniacal atmo- 

 sphere on the one side and the ammonia naturally present in the blood 

 within the vein on the other side, ought to remain fluid ; and if it did 

 remain fluid, this would tend to confirm the ammonia theory by 

 making it appear that the volatile material was the same at both ends 

 of the tube. But, to my disappointment, I invariably found that if I 

 drew away the tube after a few minutes only had elapsed, there was 

 already a clot in its extremity ; in other words, the ammonia had 

 diffused from the end of the tube into the blood within the vein as 

 into a non-ammoniacal atmosphere. This experiment alone, if duly 

 considered, would, I think, suffice to show that the blood does not 

 contain enough ammonia to account for its fluidity. 



