THE BLOOD. 259 



of the body, after removal of the contents of the alimentary canal, 

 soaking them in water for twenty-four hours, and then expressing 

 them. All the washings are collected and weighed. A given 

 volume of the normal defibrinated blood, treated with carbon 

 monoxid so as to give it uniform color, is then diluted with water 

 until its tint is identical with that of the washings similarly treated 

 with carbon monoxid. From the quantity of water necessary to 

 dilute the blood the quantity of blood in the washings is readily 

 determined. The animal having been previously weighed and the 

 weight of the contents of the alimentary canal deducted, the ratio 

 of the total weight of the blood to the weight of the body at once 

 becomes apparent. By this method it has been shown that the ratio 

 of blood to body- weight in a human adult is i : 13; in an infant, 

 i : 19; in a dog, i : 13; in a cat, i : 21. Thus an adult man of 75 

 kilos weight would have 5769 grams of blood. 



The amount of blood in the different organs has been determined 

 by ligating the blood-vessels in the living animal, removing the organ, 

 and after allowing the blood to escape subjecting the tissues to the 

 chromometric methods described abovey^ According to Ranke, the 

 volume of the blood is distributed as follows: Heart, lungs, arteries, 

 and veins, J; liver,_^_muscles, J; other organs, J.// 



Generaf-Composition. TEe results of the analyses of the blood 

 will vary with the animal and the methods employed. The following 

 table, taken from Gad, shows the average composition, expressed in 

 whole numbers, of horse's blood. In essential respects the ratio of 

 the constituents in human blood would not be materially different. 



One thousand parts of blood contain: 



{Water, 200 200 

 f Hemoglobin, : 116 

 Solids, 128 < Other organic matter, 10 



(Salts, 2 



fWater, 604 604 



Fibrin, . 7 



Albumin, 52 



Fat, i 



Other organic matter, 3 



Potassium and sodium salts, 4 



Calcium and magnesium salts, i 



Plasma, 672 -j 



L Solids, . 68 



CHEMISTRY OF COAGULATION. 



The changes which eventuate in the formation of fibrin, and 

 hence all the subsequent phenomena of coagulation, are chemic in 

 character; but as these changes take place in organic compounds the 

 composition of which is but imperfectly known, the intimate nature 

 of the process is quite obscure. All the theories which have been 

 advanced in explanation, though approximating the truth, are more 

 or less incomplete and in some respects contradictory. Since the 



