80 PHYSIOLOGY. 



In certain disordered conditions of the blood the surface of the 

 clot is not unfrequently covered with a layer of fibrine nearly free 

 from colour, and known as the huffy coat. This is commonly looked 

 upon as positive evidence of the existence of inflammation. Such is not 

 really the case, however, since it is seen in very opposite conditions 

 of the system, as in chlorosis. In inflammation the amount of fibrine 

 is really increased, and the coagulation of the blood is much retarded. 

 This allows the corpuscles time to sink to the bottom, leaving the 

 upper part of the clot composed of fibrine alone, which is nearly 

 destitute of colour and very tenacious in its character, while the 

 lower part obtains its deep red colour from the presence of the red 

 particles. The layer of fibrine in its slow coagulation undergoes 

 contraction of its edges, thus giving rise to the cupped appearance of 

 inflammatory blood. The bufly coat is also seen in the blood of 

 pregnant females ; and also in that of chlorotic patients, in whom 

 the fibrine is relatively in excess over the red corpuscles. 



In idiopathic fever the amount of fibrine is lessened ; should 

 inflammation supervene, however, the fibrine is increased. The 

 increase here is not due to the febrile condition, but to the local inflam- 

 mation, which, according to Andral, is always accompanied by an 

 increment in the amount of fibrine. 



The corpuscles of the blood, in coagulating, apply themselves to 

 each other so as to resemble piles of money. It is said that in 

 inflammatory blood they are more closely applied, and the areolse 

 between the piles are larger than in healthy blood. Fig. 16 represents 

 this arrangement, and the shape of the corpuscles. 



The materials of the nutri- 



Y'lg. 16.* tive process being prepared in 



^ the blood, every tissue and 



^i>xf\ ^-o every organ attracts from it 



^- ^^ ^^ — particles similar to itself, or 



metamorphoses the proximate 

 principles of the blood into its 

 own elements. The blood is 

 ® @ distributed to the tissues by the 



capillary system of vessels, 

 with a degree of minuteness 

 varying with the activity of the nutritive operations taking place in 

 the individual parts. It is in the capillary system that all nutri- 

 tion takes place, the plastic material being selected, as before de- 

 scribed, by the component cells of the tissue to be nourished. 



The mode in which the tissues are developed by cells, has already 

 been explained. It was then shown that in the production of any 



* A. Blood-corpuscles seen on their flat surface, and edge. B. Congeries of bloodcorpus- 

 cles in columns. 



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