The effect produced is more like the pricking of numerous needles. It is felt not only upon the tongue and palate, but wherever the part tasted comes into contact with the lips, roof of mouth or any delicate membrane. It is not perceived where this contact does not occur. The acridity of the onion and horse-radish is perceived at once and often affects other parts than those with which it comes into direct contact. 2. The Acrid Principle Is Not Always Volatile.--This is shown by the fact that large quantities of the mashed or finely grated corms of the Indian turnip and allied species, produced no irritation of the eyes or nose even when these organs were brought into close contact with the freshly pulverized material. This certainly is in marked contrast with the effect produced by freshly grated horse-radish, peeled onions, crushed mustard seed when the same test is applied. It seems fair to assume that in the latter case some principle that is volatile at ordinary air temperatures is present. The assumption that such principle is present in the former has no room. In order to test this matter further a considerable quantity of the juice of the Indian turnip was subjected to careful distillation, with the result that no volatile principle or substance of any kind was found. Various extractive processes were tried by using hot and cold water; alcohol, chloroform, benzene, etc. These failed in every instance to remove any substance that had a taste or effect anything like that found in the fresh Indian turnip. 3. The Acrid Principle Is Not Soluble in Ether.--Inasmuch as various works on pharmacy made the claim that the active or acrid principle of the plants in question was soluble in ether, this was the next subject for investigation. The juice was expressed from a considerable quantity of the mashed Indian turnip. This juice was clear and by test was found to possess the same acrid property as the unmashed corms. Some of the juice and an equal quantity of ether were placed into a cylinder and well shaken. After waiting until the ether had separated a few drops of the liquid were put into the mouth. For a little time no result was perceived, but as soon as the effect of the ether had passed away the same painful acridity was manifest as was experienced before the treatment with the ether. A natural conclusion from this test was that the acridity might come from some principle soluble in ether.