bitch.”[145] That Pliny did not put great faith in many of the things which he relates is clearly proved by several passages of his book, and among others by the following: “One can hardly relate without laughing, some things, which, however, I will not omit, because they are found already written. They say that the ox has a small stone in the head, which it spits out when it fears death; but if its head be suddenly cut off, and the stone extracted, this, worn by a child, helps it in wondrous manner to cut its teeth.”[146] In Book XXXI, Pliny speaks of various waters—mineral, thermal, etc.—especially from the medical point of view. It was already known in those days that those waters were most active agents. And in this respect a fact which the author relates in Chapter VI of Book XXV is worth mentioning: “When Caesar Germanicus moved his camp beyond the Rhine, there was found, in the whole maritime tract of the country, only one spring of fresh water, the drinking of which, within two years, produced the fall of teeth and a loosening of the knee-joints. The doctors called these evils stomacace and scelotyrbe.” Sea salt and nitre are of use, according to Pliny, against various maladies of the teeth and mouth. He counsels the application of salt on lint to the ulcers of the oral cavity, and to rub it on the gums when they are swollen. To prevent diseases of the teeth, it would be advantageous, every morning before breaking one’s fast, to keep a little salt under the tongue until it is dissolved. Against the pain of the teeth it would be beneficial to use common salt dissolved in vinegar, or nitre in wine. “The rubbing of the blackened teeth with burnt nitre gives them back their natural color.”[147] The prophylactic remedies against odontalgia believed in, at that period, were sufficiently numerous, and, among many other such things, Pliny informs us that in order not to be subject to toothache, it is sufficient to wash the mouth three times a year with the blood of the tortoise.[148] Analogous virtue was also attributed to the brain of the shark, which was boiled in oil, and this put by for washing the teeth with once a year. Besides the many anti-odontalgic remedies so far related, several others are found enumerated in Chapter XXVI of Book XXXII: