100 HAND-BOOK OF PHYSIOLOGY. 



Fibrin. In considering the functions of fibrin, we may exclude the 

 notion of its existence, as such, in the blood in a fluid state, and of its use 

 in the nutrition of certain special textures, and look for the explanation 

 of its functions to those circumstances, whether of health or disease, 

 under which it is produced. In haemorrhage, for example, the formation 

 of fibrin in the clotting of blood, is the means by which, at least for a 

 time, the bleeding is restrained or stopped; and the material or blastema 

 which is produced for the permanent healing of the injured part, con- 

 tains a coagulable material identical, or very nearly so, with the fibrin of 

 clotted blood. 



Fatty matters. The fatty matters of the blood subserve more than 

 one purpose. For while they are the means, in part, by which the fat of 

 the body, so widely distributed in the proper adipose and other textures, 

 is replenished, they also, by their union with oxygen, assist in maintain- 

 ing the temperature of the body. To certain secretions also, notably the 

 milk and bile, fat is contributed. 



Saline Matter. The uses of the saline constituents of the blood are, 

 first, to enter into the composition of such textures and secretions as natu- 

 rally contain them, and, secondly, to assist in preserving the due specific 

 gravity and alkalinity of the blood, and in preventing its decomposition. 

 The phosphate and carbonate of sodium, to which the blood owes its 

 alkaline reaction, increase the absorptive power of the serum for gases. 



Corpuscles. The important use of the red corpuscles is in relation to- 

 the absorption of oxygen in the lungs, and its conveyance to the tissues. 

 How far the red corpuscles are actually concerned in the nutrition of the 

 tissues is quite unknown. 



The relation of the colorless corpuscles to the coagulation of the blood 

 has been already considered; of their functions, other than are concerned 

 in this phenomenon, and in the regeneration of the red corpuscles, 

 nothing is positively known. 



