Page:Defensive Ferments of the Animal Organism (3rd edition).djvu/190

 interrupted. Pieces to which coagulated blood adheres, which cannot easily be removed, are rejected. Finally, they are placed in a mortar and broken up with a pestle, by which process the last traces of blood are eliminated; and then the connective tissue can be removed. We now have a snow-white tissue, which is immediately boiled. The whole process takes from one to at most three hours, according to the kind of tissue employed.

The extraction of blood can also be effected by thoroughly washing out the organ through the blood-vessels; but in this case, the organ must be washed out again after being broken up. If the extraction presents any difficulties, one can often attain one's object by covering the tissue in the fresh state with a very thick layer of common salt. The mixture is allowed to stand for two to six hours in an ice-chest; the salt is then dissolved, and the washing carried on in the usual manner. One must never preserve an organ from which the blood has been incompletely abstracted, in any particular manner, with the intention of completing the process later on. All preservation media produce coagulation and alteration of the blood. The smallest blood-vessels always contain, in that case, small quantities of blood constituents. We must also give particular warning against the use of bleaching agents, as, for instance, hydrogen peroxide. The