1863.] 585 



a sheep a long vulcanized india-rubber tube, T, adapted by means of 

 short pieces of glass tube at its extremities, both ends being con- 

 nected with the vessel so that the current of blood might be per- 

 mitted to flow through the tube, and then continue its natural 

 course. When it had been ascertained that the blood was cir- 

 culating freely through the tube, which could be readily done by 

 placing the finger on the cardiac aspect of the vein, which was 

 then made to swell if the circulation was proceeding through the 

 tube, pieces of string well-waxed were tied at intervals of about 

 2 inches round the tube, which was thus converted into a number 

 of air-tight receptacles containing blood, which certainly had no 

 opportunity for the escape of ammonia. The tube was then re- 

 moved, and I found, in accordance with the view which I was then 

 disposed to entertain, that the blood, instead of coagulating com- 

 pletely in a few minutes as it would have done if shed into a cup, 

 remained partially fluid in these receptacles after the lapse of three 

 hours. But I have since found that if the experiment be repeated 

 in the same way as regards its earlier stages, and if, after a few of 

 the strings have been tied on, the tube be cut across, the blood 

 which is in the part of the tube in the vicinity of the air, just like 

 that which is in the air-tight receptacles, remains fluid in part for 

 two or three hours. In short, that my precautions in ensuring that 

 these receptacles should be air-tight were, in so far as they applied 

 to that object, utterly unnecessary. I mention this partly as an illus- 

 tration of the deceptions to which one is liable in this inquiry, and 

 partly because the experiment thus modified seems to tell as clearly 

 against the ammonia theory as the original one seemed to tell in 

 favour of it. Those receptacles which had been formed by the ap- 

 plication of ligatures before the tube was opened afforded certainly 

 no opportunity for the escape of ammonia, and yet in them the 

 blood coagulated as quickly as in those which had communication 

 with the air implying that facility for the evolution of ammonia 

 does not in itself affect the process of coagulation at all. 



How then, it may be said, is the persistent fluidity of the blood 

 under these circumstances to be explained ? That will become more 

 obvious than I can make it at present in the sequel; but in the 

 mean time I may observe that there are probably two explanations : 

 one is, the coolness of the tube, and the other, far more important, 



