THE THIRD HUXLEY LECTURE 535 



blood and serum, which, undergoing decomposition in its interstices, grew more 

 irritating the longer the process continued ; whereas the metal gave no hold 

 to the organic liquids, which w^ere shed unaltered as fast as the}^ were effused. 

 From these and other analogous considerations, I taught my class at that time 

 that decomposition of the organic liquids was the essential cause of suppuration. 



The coagulation of the blood, while it is a matter of fundamental importance 

 in physiology, has peculiar interest for the surgeon, on account of the special 

 feature of coagulability of inflammatory exudations and the part played by 

 lymph in the healing of wounds and various other pathological phenomena, 

 such as the sealing of divided arteries by blood-clot. Towards the close of 

 the investigations which I have been describing there was published another 

 successful Astley Cooper Prize essay. Coagulation of the Blood having been the 

 subject selected by the judges for the competition. The author of this dis- 

 sertation, the late Dr. Richardson, propounded the new theory that the 

 solidification of blood shed from the vessels was due to the escape of ammonia, 

 which, as he believed, held the fibrine in solution. I was at first much struck 

 by the evidence with which he supported this view, and my first experiments 

 on the subject were made with a view to strengthening that evidence where 

 it seemed to me weakest. 



In one of these, a sheep having been placed under chloroform, I sought 

 by means of a common tourniquet to constrict the thigh so extremely as to 

 prevent the ammonia from escaping when the vessels were divided, and so keep 

 the blood fluid in spite of amputation. Rigidity of the muscles prevented me 

 from carrying out my intention ; but I tied a bandage firmly round the foot, 

 below the joint where the butcher removes it, so as to retain the blood, and, 

 as far as might be, the ammonia also. The foot being severed, I took it home, 

 and, having raised a portion of the skin so as to expose a subcutaneous vein, 

 I investigated the state of the blood in it. I found it indeed fluid, with one 

 exception, full of significance, though I did not see its import at the time. viz. 

 where the cord used by the butcher for tying the feet together had pinched 

 the veins against the bone, there, and there only, was the blood in them coagu- 

 lated. I remember being a little disa})pointed, as well as puzzled by tliat 

 appearance. It was not in harmony with the theory in which 1 was at the 

 time disposed to believe. And yet how replete were the facts with possible 

 instruction ! Compression of the veins had certainly given no o]-)portuiiity 

 for escape of ammonia. It is equally certain that the cord (.lid not make the 

 blood coagulate by any direct action upon it : for tlie cord, so long as it remained 

 in position, kept the parts of the veins whirli it compressed empty of blood. 

 It is clear that the effect was due to the action of tlie cortl upon the walls of 



