THE BLOOD 435 



bottom of the vessel. It contains a large proportion of nutritive material 

 in the form of albuminous constituents, amongst which fibrinogen, serum- 

 globulin, and serum-albumin are the most important, and it is also the 

 solvent of many other bodies on their way to the tissues, or which result 

 from the decay and disintegration of the various organs. Thus sugar, 

 fats, urea, uric and hippuric acids, cholesterin and lecithin, and many 

 salts are constant constituents. The following table shows the results 

 obtained from the analysis of the blood-plasma of the horse by two excel- 

 lent chemists. No. I being the result obtained by Professor Hoppe Seyler 

 and No. 11 that of Professor Hammarsten. 



Hoppe Seyler only examined the blood-plasma of one horse; Professor 

 Hammarsten of three, of which he took the mean. 



No. I. No. II. 



Water 908-4 917-6 



Solids 91-6 82-4 



Total albuminous bodies 77-6 69-5 



Fibrin 10-1 6-5 



Globulin — 38-4 



Serum albumin ... ... ... — 24-6 



Fat 1-21 



Extractives ... ... 4 



Soluble salts ... 6- 



Insoluble salts ... ... ... 1 ' 



The Coagulation of the Blood. — When the blood is withdrawn 

 from the body, it sets, coagulates, or clots, becoming converted from a fluid 

 into a jelly. This process occasionally occurs in disease, whilst the blood is 

 still contained within the vessels. It takes place in different animals with 

 various degrees of rapidity; thus in the blood of birds less than a minute 

 sutiices to complete the change, while a quarter of an hour or twenty 

 minutes may elapse before the blood of the horse becomes a solid mass. 

 Violent muscular eftbrts made by the animal before the blood is drawn, or 

 the rapid cooling of the blood, eft'ected by surrounding the vessel into which 

 it is drawn with ice, retard coagulation almost indefinitely. If the process 

 of coagulation be carefully watched, it will be seen that on account of the 

 corpuscles being heavier than the plasma, they sink through that fluid, 

 their descent being aided by their disposition to adhere together by their 

 broad surfaces, forming rouleaux (see fig. 181), and so presenting their 

 edges to the fluid. The white corpuscles, though heavier than the plasma, 

 are lighter than the red, and hence form a thin layer on the surface of the 

 latter, the whole being surmounted by a moderately thick layer of plasma. 

 Whether this separation of blood into layers have taken place or no, the 

 whole mass becomes first viscous and then solid, the difference resembling 



