FI'BBINE is an organic compound, occurring both in animals and plants. In its chemical composition it closely resembles albumen and caseine, and it was until recently believed that these three substances possessed a common radical, to which the name proteins (from proteno, I am first) was given, the proteine being regarded as the primary basis of all the tissues of the body. Hence we frequently find F. described as one of the proteine bodies.
F. is mainly distinguished from the allied substances, albumen and cascine, by its separation in a solid state, in the form of extremely delicate filaments or lacrelits, from any fluid in which it is dissolved, very shortly after the abstraction of the latter from the organism.
Animal F., which is of the greatest physiological importance, occurs principally in the blood, the lymph, and the chyle. In order to obtain it in a state of purity, we beat or stir the blood with a bundle of twigs, to which the F. adheres in strings. The impure F. thus obtained is then rinsed with water, boiled with alcoho', and ether—to remove fatty matters—and dried. In healthy venous blood, it scarcely ever amounts to 3 in 1000 parts, its average quantity being 2.3. Small, however, as its amount is, it varies more than any other constituent of the blood, and in acute inflammatory diseases sometimes exceeds its average by v or 0 times. Moreover, arterial blood contains more F. than venous blood. In the lymph and chyle, it occurs in considerably less quantity than in the blood. In inflammatory exudations, we find F. in the contents of the serous cavities—as, for example, of the pleura and peritoneum—and on the mucous membrane (as in croup); in these cases, it usually occurs in a state of spontaneous coag ulation.
There are good physiological reasons for believing that F. is formed from albumen, and not directly from the food; and as F. contains a little more oxygen than albumen, it has been inferred that it is formed from the latter by a process of oxidation As, however, more F. is found in the blood in pneumonia—when a considerable portion of the lungs is rendered impervious to air—than in almost any other disease, we are inclined to adopt the opposite hypothesis, that the augmentation of the F. in inflammatory blood is caused by an insufficient supply of oxygen. When oxygen is abundantly Introduced into the blood, the F. rapidly undergoes further transformation. on the other hand, when, in consequence of impeded respiration, the quantity of oxygen conveyed to the blood is not sufficient to effect the further normal oxidation or transformation of the F., we have an accumulation of that constituent in the circulating fluid.
It has, however, been a disputed question, whether F. is produced in the elabora tion or in the disintegration of the tissues. For the discussion of this subject, and of the other points connected with F,, we must refer to Lehmanu's Physiological Chemis try, vol. i. pp. 361-864.
The substance forming the mass of flesh or muscular tissue was formerly regarded as identical with coagulated blood-fibrine. The two substances are, however, chemic ally distinct, and the muscle-fibrine will be described under its new chemical name, SYNTONINE (from sunteinein, to contract or render tense).