Fibrine, a nitrogenous organic substance, existing in a fluid form in the blood and lymph, and capable of spontaneous coagulation when withdrawn from the vessels of the living body. Vegetable fibrine, a substance analogous to it in composition, is found in the newly expressed juices of plants, particularly of the grape, when these are allowed to stand for some time, and the gelatinous substance that is deposited is washed free from the coloring matter associated with it. A similar substance exists also in wheat flour, being separated in the gluten. Fibrine is obtained from freshly drawn blood by taking up the ropy portions that adhere to a twig with which it is stirred, and thoroughly cleansing these of coloring and soluble matters by washing. It is a soft white substance, and becomes on drying yellowish, brittle, and semi-transparent. Numerous analyses have been made of the fibrine, albumen, and caseine derived from vegetables used for food-the albumen from the clarified juice of turnips, asparagus, etc, and the caseine from beans and peas; and the results prove a close analogy of composition not only among themselves, but with the chief constituents of the blood, animal fibre and albumen.
One of the analyses of animal tibrine by Sherer might almost equally well be given for either of the other substances, or indeed for the caseine of milk, which is a similar substance. The following is one of many quoted by Liebig: carbon, 54.454; hydrogen, 7.069; nitrogen, 15.762; oxygen, sulphur, phosphorus, 22.715. Fibrine is exceedingly important as an ingredient of the blood, since it is due to its presence alone that the blood is capable of coagulating in wounds or after the ligature of blood vessels, and thus arresting the haemorrhage which would otherwise continue to take place. Its proportion in the blood is rather over two parts per thousand, in the lymph about one part per thousand.