34 dr davy's miscellaneous observations on the blood. 



ing. Further, I have found the ash of hsematine prepared by a more elaborate 

 process also feebly alkaline ; and the latest analyses of the several ingredients of 

 the blood, those most to be depended on, indicate the same.* May not this 

 difference, slight though it appears, warrant the conjecture, that as in the egg, so in 

 the blood, there may be an action of a galvanic kind between its several proxi- 

 mate parts ? And may not the differences which are known to exist between the 

 serum and the red corpuscles be adduced in favour of the conjecture? 



VI. On the Coagulation of the Blood. 



Of the many hypotheses which have been advanced at different times to 

 account for the coagulation of the blood, each has been supported, as hypotheses 

 usually are, by some facts, but few of them have for any length of time main- 

 tained their ground, facts having been adduced hostile to them. 



Of the latest hypotheses brought forward, one is that of Dr Richardson, 

 briefly designated the ammonia-theory, to which I have already adverted ; 

 another is that of Professor Lister, in which he considers the phenomenon as 

 mainly depending, out of the body, on a kind of catalytic action produced by the 

 contact of any foreign substance, and, within the body, as owing to an analogous 

 cause, contact with a part, either dead or quasi dead, — as he supposes a tissue to 

 be under the influence of inflammation.! 



This hypothesis, as it appears to me, is open to certain objections. I shall now 

 notice merely a few of the facts which seem to me most opposed to it. 



1 . Were it true, ought not the phenomenon of coagulation to take place in every 

 instance in which dead matter comes in contact in the living body with the blood ? 

 Instances of ossification, in which concretions of phosphate of lime are formed in 

 the arterial coats, and often project into the vessels themselves, — concretions 

 differing but little from the " tartar," deposited so often on the teeth, and in- 

 organic, — are familiar to every one acquainted with pathological anatomy, and 

 yet in the majority of these cases the coagulation of the blood has not taken place 



2. In instances of aneurism, with a rupture of the vessel, the seat of it, a 

 coagulum of blood is invariably formed, though in contact with parts which, it 

 may be presumed, until the contrary is proved, still retain their vitality. 



3. Examples of the coagulation of the blood in the veins, in the arteries, and 

 in the ventricles of the heart, during life, in persons reduced to a feeble state by 



attracted by the magnet, the coal after cooling having been reduced to powder. The particles of its 

 ash, after the charcoal had been burnt off, were also similarly attracted. The magnet used, it may 

 be .mentioned, was a needle that had been magnetised by a foetal torpedo, and which (as the result 

 showed) still retained its power, after the elapse of 32 years. The residuary ash, on the addition of 

 a little water, showed so feeble an alkaline reaction, that it was hardly as well marked as that of the 

 saliva. 



* Lehmann's " Physiological Chemistry," ii. pp. 160, 212. 



f Proceedings Roy. Soc. Vol. xii. p. 580. 



