DR DAVY'S OBSERVATIONS ON BLOOD AND MILK. 67 



the tube is far more elastic than the other, after the manner of the middle arterial 

 coat. 



Other instances might be given, tending to shew the same disposition on the 

 part of coagulable lymph to a certain regular ai-rangement of its parts, as it were, 

 of a nisus formativus, in the act of coagulation. In examining the huffy coat, or 

 the fibrinous masses which are so commonly met with after death in the right 

 cavities of the heart, it is not uncommon to find in them, when divided, cavities 

 containing serum resembling cysts. And in the ventricles of the heart, and the 

 aorta and the principal veins, especially the iliac and femoral, fibrinous concre- 

 tions, as it is well known, are often found after death from lingering diseases, in 

 which a puriloid matter is contained, as in a sac, — a matter which has been imi- 

 tated by Mr Gulliver, by the coction of lymph, at about the temperature of the 

 human body, and which, previous to his experiments, had been considered as 

 pus, and, erroneously, as the product of inflammation. 



I would ask in conclusion, is not this disposition of coagulable lymph called 

 into play in other occasions during life, and may it not serve to explain certain 

 appearances which are commonly accounted for in a different manner, such as 

 the cysts which so rapidly form in the instance of aneurisms, the consequence 

 of wounds, and the lining membrane of the sacs of false aneurisms, which is hardly 

 in appearance distinguishable from the inner coat of the artery with which it is 

 continuous ? 



4. On the Effect of Serum in promoting the Coagulation of Milk. 



There is a marked difference, as is well known, between the albuminous part of 

 the serum of the blood and that of milk, — ordinary cow's miUv,— viz., that, whilst 

 the former is coagulated by a temperature below the boiUng point of water, the 

 latter, in its fresh state, is not so affected, even by ebullition, but, on the contrary, 

 has its natural tendency to coagulate, connected with the absorption of oxygen 

 and the formation of an acid, retarded. A priori, perhaps, it would harldly be 

 expected, as regards the property of coagulation, that the one fluid mixed with 

 the other would have any material effect. But that it is not so, I have found on 

 trial. Milk, I find, when mixed with serum in certain proportions, is coagulated 

 by heat. I shall notice some results obtained, using mixtures of the serum of the 

 blood of the sheep, which coagulated at about 170° Fah., and cow's milk. 



Equal parts of the two remained liquid at 170°, and coagulated about 175^ 

 The coagulum was of an opaque white, very little softer than the coagulum of 

 the serum alone. Mixed with water it did not render it milky ; and the watery 

 infusion was not rendered turbid by acetic acid, and only in a very slight degree 

 by the nitric acid. 



VOL. XVI. PART I. p 



