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CHAPTER XXVII. 



THE BLOOD. ITS QUALITIES. ITS PHYSICAL ANALYSIS. THE 



LIQUOR SANGUINIS. THE BLOOD PARTICLES. THE QUANTITY OF 



BLOOD IN THE BODY. THE PHENOMENON OF COAGULATION. 



THE CONSTITUENTS OF THE BLOOD. ANATOMY OF THE BLOOD 



CORPUSCLES. THEIR MODE OF ORIGIN. THEIR FUNCTION. 



THE CHEMICAL ANALYSIS OF THE BLOOD. CHANGES PRODUCED 



IN THE BLOOD BY VENESECTION, AND BY DISEASE. 



THE blood is a fluid, whicli is always circulating in numberless 

 canals among the various tissues and organs of the body ; it is the 

 source whence those tissues and organs draw their nutriment, and 

 from which the glands derive the materials for their several secre- 

 tions. The lymph and the chyle are poured into it as tributary 

 streams ; the former conveying to it, in solution, materials yielded 

 up by the wear and tear of the tissues, and also derived from 

 without ; the latter bringing to it new matter formed by the digestive 

 process. 



The blood is a thick fluid, apparently homogeneous, of high 

 specific gravity (1041 1082, Simon), and of a red colour, in all 

 the vertebrate and most of the invertebrate classes, but exhibiting 

 differences of colour, according to circumstances to be noticed here- 

 after. A saltish taste, and a peculiar heavy odour, must also be 

 reckoned among its characters. If allowed to rest in a cup, or 

 other vessel, it exhibits a remarkable spontaneous analysis. In 

 the course of from ten minutes to half an hour it separates into a 

 solid portion (the crassamentum) and a fluid portion (the serum) . 

 The latter, if carefully decanted off, will be found to be a clear 

 straw-coloured fluid, the menstruum of that great variety of mate- 

 rials which is held in solution or suspension in the blood. Albumen 

 in large quantity, salts, and various organic matters, are dissolved 

 in it ; oily matters are suspended in it ; and prior to coagulation 

 fibrine is held in solution, and coloured and other particles are 

 diffused in infinite multitudes throughout it. 



An artificial physical analysis of the blood, first suggested by 

 Miiller, shows satisfactorily the true relation of its various con- 

 stituents. If the blood of an animal whose coloured particles are 



