304 CIRCULATION OF NUTRITIVE FLUID. 



unite with it. In fact, the white corpuscles are not found in company 

 with the red, in the ordinary coagulum, but rather with the fibrinous 

 portion ; and when they are peculiarly abundant, as they usually are 

 in Inflammatory blood, they may form a considerable proportion of the 

 buffy coat. 



537. The Buffy Coat may present itself, without the least increase 

 in the normal quantity of Fibrine, and without any approach to the 

 Inflammatory state ; simply because the Fibrine is present in exces- 

 sive amount, in relation to the amount of Red corpuscles, the latter 

 being much below their usual proportion. Thus in severe Chlorosis, 

 the bufiy coat is almost as strongly marked, as in the severest Inflam- 

 mation ; but the two conditions are at once distinguished by the rela- 

 tive proportions of solid matter in the blood, as indicated by the size 

 of the Coagulum. For in Chlorosis, the coagulum is very small, in 

 consequence of the reduced proportion of Corpuscles, and is almost 

 invariably found floating in the serum ; whilst in the ordinary Inflam- 

 matory condition, it is of full size, frequently adhering to the side of 

 the vessel. 



CHAPTER VI. 



OF THE CIRCULATION OF THE BLOOD. 

 1. Nature and Objects of the Circulation of Nutrient Fluid. 



538. THE nutritive fluid, the elements of which are thus partly taken 

 up and prepared by the Absorbent system, but are in great part also 

 imbibed through the Blood-vessels distributed upon the walls of the 

 digestive cavity, and assimilated by the liver ( 493), is carried into 

 the various parts of the system, by the act of Circulation. This move- 

 ment answers various purposes. It furnishes all the tissues, which are 

 to derive nutriment from the Blood, with a constantly-renewed supply 

 of the materials which they severally require ; and in this manner it is 

 subservient to the growth, not only of those tissues which form part of 

 the solid structure of the body, but also of those various cells, covering 

 its free surfaces, which are being continually cast off and renewed, and 

 which, in the course of their development, separate from the blood the 

 products that are to perform ulterior purposes in the economy, or are 

 to be removed as altogether effete. Thus the Circulation is subservient 

 to the functions of Nutrition and Secretion. In the exercise of these 

 functions, different materials are drawn from the blood by the several 

 tissues it supplies. Thus the nutrition of the muscle requires fibrine ; 

 that of the nerve requires fatty-matter ; that of the bone draws off gela- 

 tine and earthy salts ; that of the hepatic cells removes the fatty matter 

 and other elements of bile ; that of the milk-cells (during lactation) 

 separates albuminous, fatty, and saccharine substances; and so on. 

 Thus various portions of the blood, when returning from the several 



