Purgatives will act as hepatic depressants and lessen the secretion of the liver by removing from the intestine the bile which would otherwise be re-absorbed, and by hurrying out also •the food which might yield materials for the secretion of new bile; but some substances, such as calomel, castor-oil, gamboge, and magnesium sulphate, were found by Rutherford to depress the secretion in cases where the bile-duct was ligatured and the animals fasting, so that in all probability the effect of the drugs in diminishing the secretion was due to their lowering the blood-pressure in the liver.