CHAPTER VIII. 

 BLOOD AND LYMPH. 



The blood and lymph are the cellular fluids circulating 

 about the body in the circulatory and lymphatic systems and 

 providing for body-nutrition. They convey to the tissues 

 the gaseous, fluid, and solid pabulum required in their ana- 

 bolism or upbuilding, and bear away from them the waste- 

 products of their katabolism or downbreaking. 



Blood: On examining fresh blood under the microscope 

 we observe large numbers of free straw-colored cells, with 

 here and there a colorless cell, suspended in a clear homo- 

 geneous fluid. The blood, then, consists of two portions a 

 fluid .portion, the plasma, and free blood-cells or corpuscles 

 suspended in it. 



The corpuscles, again, are of three kinds red blood-corpus- 

 cles, white blood-corpuscles, and blood-plates. 



The plasma comprises about three-fifths of the blood ; the 

 corpuscles about two-fifths. 



The blood may be regarded as a fluid tissue, the corpuscles 

 being the cellular elements and the plasma the intercellular 

 substance. It differs from other tissues, however, in that the 

 intercellular portion is not produced by the activity of the 

 blood-cells themselves, but is derived from absorption. The 

 blood belongs to a class of tissues that is sui generis, different 

 from and coordinate with the classes of epithelium, connec- 

 tive tissue, etc., which make up the fixed tissues. Owing to 

 the facility with which it can be examined and the significant 

 changes which it exhibits in various diseases, the histology of 

 the blood is a matter of great importance in practical medi- 

 cine. 



Blood-plasma, or liquor sftnguinis: This is a clear, homogene- 

 ous, colorless fluid comprising about three-fifths of the volume 

 of the entire blood. It consists of water holding in solution 



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