FORMATION OF LIQUOR SANGUINIS. 731 



-wards traverse the liquor sanguinis to reach the tissues. The elabo- 

 ratiye office of the corpuscles, and their influence on the composition 

 and formation of the liquor sanguinis, are undoubted. 



The fibrin of the blood is believed to be derived from the albumen, 

 of which it is said to be a modified, degraded, or more oxidized condi- 

 tion. It has been stated that, on passing a galvanic current through 

 a solution of albumen, a concretion of a substance resembling fibrin 

 becomes attached to the positive pole (Smee); but this deposit may 

 not be identical with fibrin. 



The blood of the hepatic and renal veins contains only a small quan- 

 tity of fibrin, and coagulates but imperfectly ; hence it has been con- 

 jectured that fibrin may be destroyed, or oxidized, in the liver and 

 kidneys. On the other hand, the blood of the splenic vein contains 

 much fibrin, coagulates very firmly, and, even when defibrinated by 

 whipping, will produce a second clot, after long exposure to the air. 

 It is thought also, by some, that the action of the muscles may give 

 rise to an appearance of fibrin in the blood ; for on injecting defibrin- 

 ated blood into the arteries of a recently detached animal's limb, the 

 blood returning by the veins is found to contain fibrin, whenever the 

 muscles have been excited to repeated contractions by galvanism. 



The amyloid and saccharine matters are probably added to the 

 blood chiefly from the liver, the inosite from the muscles. The nitro- 

 genous creatin and creatinin are probably products of the decomposi- 

 tion of albuminoid matter. The coloring matter is possibly, in part, 

 newly formed in the lungs ; but previously existing cruorin may per- 

 haps be used again. 



The nutritive changes, whether of waste or renovation, in the homo- 

 geneous or formless liquor sanguinis, added to those which take place 

 in the organized elements or blood corpuscles, imply a more special, 

 and more complicated, nutritive movement than that which occurs in 

 any one of the tissues or glands ; for they reciprocate with the meta- 

 morphoses of all the tissues and glands. The variety of nutritive and 

 secernent changes to which the blood ministers, and in which it itself 

 undergoes incessant corresponding alterations, is very great, and yet 

 its highly complex, but essential, constitution remains, within certain 

 limits, the same. 



The constitution of the blood is also continually changed, on the one 

 hand, by the accumulation within it, of its own effete materials, and 

 its reception of those of the disintegrated solid tissues, and, on the 

 other, by its constantly casting out of itself the various products of 

 that decay. In this way, its creatin, creatinin, and urea, and its 

 lactic and carbonic acids, enter, and then escape through the agency 

 of the renal, cutaneous, and respiratory excretions. The quantities of 

 effete extractives and of urea are small, for they are always being car- 

 ried off; if they accumulate, mischief ensues. Considering that the 

 blood is constantly drawn upon for the supply of nutriment to the rest 

 of the body, that it is intermittently and variously renewed, that it is 

 itself subject to decay in its essential structural and fluid elements, 

 and the seat of constant additions and subtractions, its composition 

 retains a remarkable unity. The complexity of the mutual relations 



