1863.] 401 



The blood employed was arterial, and not venous. At first the 

 bright scarlet colour of the blood increased somewhat, but after twelve 

 hours the bright scarlet began to assume more the colour of venous 

 blood : the cells at the same time began to shrivel. From this 

 time the blood began rapidly to grow darker and darker, when, after 

 thirty-six hours, it was almost black*. 



Virchow has shown that, by acting on the haematin contained in 

 the blood-cells by acetic acid, and subsequently boiling it, a sub- 

 stance is formed to which he gives the name of haemine, which he 

 considers to be a product in an intermediate stage between haematin 

 and pigment. The black substance formed by oxidation may pro- 

 bably be found to be analogous to, if not identical with, Virchow's 

 haemin. I found in this blood, at the end of thirty-six hours, small 

 masses, which had, under the microscope, the appearance of fibrin. 

 A small portion of the same blood as that used in the experiment was 

 set aside till the completion of the experiment, when it was examined, 

 but no fibrin was found. 



Likewise in the glass E, although the gas was passed through it 

 without heat, no fibrin was found, proving that temperature had also 

 an effect on the production of fibrin. This experiment was repeated 

 many times : in all cases the blood assumed the black colour, but I 

 did not invariably find fibrin. 



The appearance of fibrin in some cases, and the non-appearance in 

 many others, seemed at first sight to be inexplicable, though I shall 

 be able to demonstrate, in a later portion of this paper, that the 

 result may be explained upon the hypothesis that the alkaline salts 

 were in relative excess in those cases where the fibrin did not appear. 



In my next series of experiments, the white of an egg was added to 

 about 4 oz. of the defibrinated blood. The egg- album en at first had 

 a tendency to separate and float at the top of the blood-serum, 

 although well agitated together. In these cases the blood assumed 

 the same dark colour as when it was subjected to experiment alone, 

 though it did not appear until after the serum and egg-albumen had 

 completely coalesced, which took place about ten hours after the 

 subjection to temperatures between 95 and 100 Fahr., and the 

 action of oxygen gas. At the end of thirty-six hours, the time when 

 the experiment was stopped, masses of substances were found float- 



* Crawford, about fifty years back, found that, after immersing animals in hot 

 water, no difference could be discerned between arterial and venous blood. 



