442 OF NUTRITION. 



first act of its conversion into solid tissues possessing a high degree of vitality. 

 It is absurd to suppose that the blood dies, in order to assume a higher form. 

 When withdrawn from the body, however, the Coagulation of the Blood is the 

 last act of its life ; for, if not within the influence of a living surface, it soon 

 passes into decomposition. Instances occasionally present themselves in which 

 the Blood does not coagulate after death ; and in most of these there has been 

 some sudden and violent shock to the Nervous system, which has destroyed 

 the vitality of solids and fluids alike. This is generally the case in men and 

 animals killed by lightning, or by strong electric shocks ; and in those poisoned 

 by prussic acid, or whose life has been destroyed by a blow on the epigastrium. 

 It has also been observed in some instances of rupture of the heart, or of a 

 large aneurism near it ; and a very interesting phenomenon then not unfre- 

 quently presents itself, the coagulation of the Blood which has been effused 

 into the pericardium (the effusion having taken place during the last moments 

 of life), whilst that in the vessels has remained fluid. In several of the in- 

 stances in which the blood has been found uncoagulated in the vessels, many 

 hours after death, a portion withdrawn from the body has clotted ; this would 

 seem to indicate that there is some absolutely depressing influence exercised 

 by the surrounding tissues under such circumstances, an influence of which 

 manifest evidence is afforded, by the sudden destruction of the muscular con- 

 tractility, the arrestment of the capillary circulation, and other phenomena of 

 like nature. It appears, however, that simple arrestment of Nervous influence 

 favours the coagulation of the blood in the vessels ; clots being found in their 

 trunks within a few minutes after the Brain and Spinal marrow have been 

 broken down. 



584. The length of time which elapses before Coagulation, and the degree 

 in which the Clot solidifies, vary considerably ; in general, they are in the 

 inverse proportion to each other. Thus, if a large quantity of blood be with- 

 drawn from the vessels of an animal at the same time, or within short inter- 

 vals, the portions that last flow coagulate much more rapidly, but much less 

 firmly, than those first obtained. In Blood drawn during Inflammatory states, 

 again, the coagulation is usually slow, but the clot is preternaturally firm; 

 especially at its upper part, where the Buffy coat ( 588) or colourless stratum 

 of Fibrin, gradually contracts, and produces the cup, which is usually regarded 

 as indicative of a high degree of Inflammation. Except, under the peculiar 

 circumstances just stated, the Blood withdrawn from the body always coag- 

 ulates;* whether it be kept at rest or in motion; whether its temperature be 

 high or low ; and whether it be excluded from the air, or be admitted to free 

 contact with the atmosphere.! The Coagulation may be accelerated or retarded, 

 however, by variation in these conditions. Thus, if the Blood be continually 



* Some diseases may, perhaps, be an exception; non-coagulation of the Blood is said 

 to be characteristic of the Scurvy, but this is erroneous. In very severe forms of Typhus, 

 the same has been stated to occur. 



f f[An inexplicable case, in which the complete coagulation of the blood did not take place 

 till fifteen days after its abstraction, has been published by Dr. Pollit, who adduces this 

 case in proof that there is no blood which becomes putrid before it has coagulated. The 

 patient was a man 37 years old, with acute pneumonia. The blood of a first bleeding was 

 drawn into a block-tin vessel, and set in a temperature between 46 and 52. It remained 

 liquid for eight days, the blood-corpuscles having settled to the bottom, with the liquor san- 

 guinis floating above them, exactly like serum pressed from a clot. On the ninth day, a 

 membranous pellicle began to form on the surface of the fluid, and this becoming thicker, 

 and increasing in tenacity and consistence, acquired at last- all the characters of the most 

 genuine bufify coat. The serum began to ooze from the clot on the fifteenth day : and on 



Gazzetia Medica di Milano,Gennaio 20, 1844. 



