Extensive experiments with the separate constituents of dogs’ dung have shown that with none of them employed alone can a satisfactory action be obtained. For the experiments, the organic and inorganic salts contained in dog’s dung were employed. Pure cultures of intestinal bacteria were also examined and also the intestinal juices, secretions of the gall bladder, of the pancreatic gland and secretions of the intestinal mucous membrane. The relatively best bating action was obtained with the secretion of the gall bladder; only a moderate bating action could be obtained with the juices of the pancreatic gland and the secretions of the intestinal mucous membrane. It was therefore very surprising to find and could not be foreseen that mixtures of these three secretions of the digestive apparatus alone exerted an excellent bating action, and that such mixtures not only formed a perfect substitute for the bate of dogs’ dung, but that they acted far better than the latter, without it being necessary, as was recommended elsewhere,[147] to add lime-dissolving salts to the bate, or to take measures in any other manner for the removal of the lime from the water.[148] [147] 1. See German Patent No. 200,519 or British Patent No. 5377^{08} Roehm, Esslingen. [148] 1. See German Patent of Addition No. 203,889 Roehm, Esslingen. The explanation of the effective action of such mixtures is evident from the following statements:-- Pancreatic juice contains three ferments, of which for our purpose trypsin, which decomposes albumen, and steapsin which decomposes fat, are the most important. Both ferments are contained as zymogens, that is to say in an inactive form, in the pancreatic juice. The latter therefore only gives an incomplete bating action. Gall contains ferments which have properties which are mainly fat decomposing, but are also albumen dissolving. Gall also contains the salts of gallic acids which have the power in a high degree of dissolving and emulsioning greases or fats, and among others have a great solvent action on the chloresterin contained in the skin, more particularly in the roots of the hair. As regards the fat-decomposing and dissolving action, gall is far superior to pancreatic juice. The ferments of gall are, however, also capable of energising the action of the steapsin in the pancreatic juice as a fat-decomposing ferment, that is to say of imparting to the pancreatic juice, which in a pure condition has a very slight action on fat, a high capacity for decomposing fat.[149] [149] 2. See Abderhalden, “Text-book of Physiological Chemistry,” 1906, page 555 and following.