710 SPECIAL PHYSIOLOGY. 



red corpuscles, the albumen of the white corpuscles, and that held in 

 solution in the liquor sanguinis ; this latter is said to be chiefly de- 

 rived from, or prepared by, the blood corpuscles, the globulin of which 

 is believed to escape into the liquor sanguinis, either through their thin 

 envelopes, or after their solution. These albuminoid substances are 

 of the highest nutritive value ; for they, or their derivatives, are 

 found, in larger or smaller quantity, in all the tissues and organs of 

 the body, both in the microscopic cell-elements and the intercellular 

 substance, appearing as albumen or syntonin in the nervous tissues, as 

 syntonin in the muscles, much changed, as a gelatin- or chondrin-yield- 

 ing substance in the fibrous and areolar tissues, bone, and cartilage, 

 and as elastin in the yellow ligaments and other elastic tissues. Gela- 

 tin is not found in the blood itself; but when digested, it is converted 

 into a gelatin peptone, and so becomes absorbed, as we have seen, but 

 in what state, is not yet known ; nor is its destination in the nutritive 

 processes of the body certain. Either it may serve for the direct nu- 

 trition of the gelatin-yielding tissues, or, and this is very probable, it 

 may, by itself undergoing oxidation, conserve other more important 

 tissues, and, at the same time, maintain the temperature of the body. 

 Its efficacy as administered in jellies, beef-tea, and broth, in cases of 

 sickness, especially indicates its importance as an article of diet. Fur- 

 thermore, the albuminoid substances, such as salivin, pepsin, pancre- 

 atin, and casein, found in many most important secretions, must be 

 derived from the albumen of the blood. The quantity of these formed 

 in the day is considerable, but those contained in the digestive fluids 

 are quickly absorbed into the blood again. Though so highly nutri- 

 tive, and absolutely essential to the economy, albumen, considered as 

 an organizable substance, has no metamorphic power ; though it affords 

 a fit material for metamorphic action. 



The fibrin of the blood was formerly supposed to be specially in- 

 tended for the nutrition of the muscles, their albuminoid constituent, 

 syntonin, being considered to be identical with the fibrin of the blood. 

 It is now believed that the fibrin is not so essential for nutritive pur- 

 poses as the albumen, and the small proportionate quantity in the 

 blood, as compared with other albuminoid bodies, viz., about 1 to 90, 

 is in accordance with this idea. Fibrin is more highly oxidated, or con- 

 tains more oxygen, than albumen ; hence it may be a degraded form or 

 condition of albumen, exhibiting a retrogressive change into some still 

 lower compounds. As already mentioned, it may assist in maintaining 

 some essential physical characters of the blood ; and, lastly, it plays a 

 highly important part, in causing the coagulation of this fluid. To 

 this change in the blood, the character and causes of which will be 

 hereafter discussed, the first closure of the orifices of bleeding arteries 

 and veins is often due, and further hemorrhage is thus arrested. 

 Moreover, in most acts, especially in the union of divided parts, and 

 in the healing of sores, the fibrin contained in the exuded plasma 

 coagulates, forming the first bond of union, and a matrix in which 

 nuclei or nucleated cells are developed ; further reparative changes 

 then ensue, according to the tissue which is the seat of reparation. 

 But the coagulation of exuded 'fibrin in the living animal economy, 



