214 USES OF SEPARATE CONSTITUENTS OF BLOOD. 
being, as it were, in process of organization. The albumen 
of the hlood further serves to supply the albuminoid matters 
which are required as constituents of various secretions, espe¬ 
cially those which are concerned in the digestive process, as 
the saliva, the gastric juice, and the pancreatic fluid. A 
large amount is daily drawn-off for the production of the 
peculiar ferments contained in these secretions, whose action 
upon the food is necessary for its reduction to the form in 
which alone it can he received into the circulating current. 
Hence the making of new blood involves a considerable ex¬ 
penditure of the old. 
241. The liquid in which the fibrin and albumen are dis¬ 
solved, has a considerable power of absorbing gases ; and this 
is greatly increased by the presence of the saline matters 
which it holds in solution. Hence the liquor sanguinis not 
only sustains the nutrition of the body, but can also serve, to 
a considerable extent, as a medium of communication between 
the lungs and the tissues. In this kind of activity, however, 
it is completely surpassed by the red corpuscles (§ 235). 
Independently of their use in ministering to the function of 
Respiration, there seems reason to believe that the red cor¬ 
puscles are also subservient to that of Nutrition; for a certain 
conformity which exists between the organic and mineral sub¬ 
stances they contain (§ 232), and the composition of Muscle 
and ISTerve, taken in connexion with the manifest relation 
between their number and the activity of the Hervo-muscular 
apparatus, makes it probable that they have it for their especial 
office to prepare the materials which are to be used in its pro¬ 
duction and renewal of those tissues. The saline matter of the 
blood has many important offices: thus it furnishes the mineral 
ingredients which are requisite for the production of the tissues 
and secretions; it helps to preserve the organic substances from 
decomposition; and, in conjunction with the albumen, it keeps 
up the density of the serum to the point at which it is equi¬ 
valent to that of the contents of the red corpuscles, without 
which balance the condition of the latter would be seriously 
impaired (§ 231). Finally, the fatty matters of the blood are 
subservient to two very important functions—the maintenance 
of heat, and the formation of tissue. They maintain the 
combustive process, whenever there is a deficiency of more 
readily combustible material j and they also take part with 
