THE BLOOD. 45 



tendency of the lymph to coagulation, depends ; which surely 

 is a very curious circumstance. 1 



From this observation we may be led to think, that it may 

 be useful to receive the blood more frequently into small cups, 

 instead of a basin, and to attend more carefully to the alter- 

 ation produced upon it by bleeding ; as we may by that means 

 perhaps learn to determine better what quantities should be 

 taken away in particular cases. For it would seem probable 

 that the operation is likely to have the most effect on the dis- 

 ease, in those cases where the greatest change is produced by 

 its means, on the disposition of the blood to coagulate ; and of 

 that change we can judge, by comparing the blood in the first 

 cup with that in the last; for the first cup will nearly show 

 the state of the blood at the beginning, and the last cup the 

 state of the blood at the latter part of the evacuation. 



It frequently happens that, instead of an inflammatory crust 

 over the whole surface of the crassamentum, there is only a 

 partial one, which appears in large spots or streaks. In such 

 cases I have observed, that only a part of the blood had its 

 disposition to coagulate lessened, as in Experiment xv, in 

 which some of the blood remained fluid and transparent, where 

 those streaks appeared, for some time after the coagulation had 

 begun in other parts of the surface. Now whether in those 

 cases there had been the same difference before the vein was 

 opened, or whether the whole blood had not been of the inflam- 

 matory kind, before venesection, and a part of it was changed 

 as it ran out, or as soon as the general fulness was diminished, 

 may be a question ; but the probability, I think, is much in 

 favour of its being changed during the time of the evacuation, 

 from what was observed in the last experiments. 



When I had observed that this disposition of the lymph to 

 coagulate was increased by bleeding, or by weakening the ac- 

 tion of the blood-vessels, I suspected that possibly in those 

 cases where the body was very weak, the disposition to coagu- 

 late might be so much increased, that instead of being three or 



1 That the properties of the blood can be changed by emptying the blood-vessels, 

 is likewise proved by an experiment hereafter to be related, where the blood in an 

 animal in health was found to have its disposition to coagulation increased in pro- 

 portion as the vessels were emptied, and as the animal became weaker. It may like- 

 wise be proper to mention, that though the inference is here drawn from two experi- 

 ments only, yet I have likewise observed the same appearance in other cases, which 

 I have thought unnecessary to relate. 



