1863.] 599 



large or small. We can see a final cause for this, so to speak. So 

 long as the heart is acting, circulation will be sure to go on in the 

 heart and principal trunks ; whereas, on the contrary, the more su- 

 perficial parts are liable to temporary causes of stagnation, and occa- 

 sionally to what amounts to practical severance from vascular and 

 nervous connexion with the rest of the body ; and it is, so to speak, 

 of great importance that the blood should not coagulate so speedily 

 in the vessels of a limb thus circumstanced as it does in the heart 

 after it has ceased to beat. Were it not for this provision, the surgeon 

 would be unable to apply a tourniquet without fear of coagulation 

 occurring in the vessels of the limb. As an illustration of the im- 

 portance of a knowledge of these facts, I may mention a case that 

 once occurred in my own practice. I was asked by a surgeon in a coun- 

 try district to amputate an arm which he despaired of. The brachial 

 artery had been wounded, as well as veins and nerves, and at last, 

 being foiled with the hemorrhage, he wound a long bandage round 

 the limb at the seat of the wound as tightly as he possibly could. It 

 had been in this condition with the bandage thus applied for forty- 

 eight hours when I reached the patient ; and the limb had all the 

 appearance of being dead. It was perfectly cold, and any colour 

 which it had was of a livid tint. But having been lately engaged in 

 some of the experiments which I have been describing, and having 

 thus become much impressed with the persistent vitality of the tissues 

 and the concomitant fluidity of the blood, I determined to give the 

 limb a chance by tying the brachial artery. Before I left the 

 patient's house he had already a pulse at the wrist, and I afterwards 

 had the satisfaction of hearing that the arm had proved a useful one. 



One of the two arguments in favour of activity on the part of the 

 vessels as a cause of the fluidity of the blood having been completely 

 disposed of, let us now consider the other, viz. the rapid coagulation 

 of blood shed into a basin, appearing at first sight to imply a sponta- 

 neous tendency of the blood to coagulate, such as would have to be 

 counteracted by the vessels. This also has proved fallacious. 



In the first place it appears that the coagulation, after all, does 

 not go on in a basin so suddenly as one would at first sight suppose, 

 but always commences in contact with the foreign solid. When blood 

 has been shed into a glass jar, if, on the first appearance of a film at 

 the surface, you introduce a mounted needle curved at the end be- 



2 u 2 



