Rovighi,[308] an Italian physician, drank daily a litre and a half of kephir, a preparation made by subjecting milk to lactic acid and alcoholic fermentations. He found that in a few days the products of intestinal putrefaction in his urine either disappeared or were greatly reduced. It is plain, then, that the slow intoxications that weaken the resistance of the higher elements of the body and that strengthen the phagocytes may be arrested by the use of kephir, or still better of soured milk. The latter differs from kephir in that it contains no alcohol, and alcohol in course of time diminishes the vitality of some important cells in the body. The presence of a number of the lactic acid bacteria is inimical to the growth of the bacteria of putrefaction, and so is of great service to the organism. But it is not enough merely to introduce useful microbes into the body. We must also prevent the entrance of “wild” microbes, many of which are harmful. Soil, especially when it has been manured, contains large numbers of microbes, some of which are harmful. Bienstock found that the soil of the strawberry-beds in his garden contained the bacilli of tetanus. For three weeks he swallowed some of this soil, but found that the bacteria were destroyed in his intestines, which he attributed to the action of the normal bacterial inhabitants of the alimentary canal. It is probable that if this arresting action were weakened the body would be infected by tetanus from spores of the tetanus microbe swallowed with earth or strawberries or green vegetables. Moreover, besides the organisms of tetanus, there are many other dangerous anærobic bacteria in manured garden soil. Obviously we should eat no raw food, but confine our diet rigidly to food that has been thoroughly cooked or sterilised. The exclusion of “wild” microbes and the introduction of beneficial microbes, such as those of lactic acid fermentation, must be of great service to health. I know of individuals who have derived great benefit from such a regimen. Science, even in its present imperfect condition, has many weapons by which to prevent or at least diminish the slow and chronic poisoning of the organism that leads eventually to the degeneration of the higher elements. When these elements are being destroyed by syphilis or alcoholism the struggle must be directed against these evils. It is long since we have known how to do this; that success has not been greater is due to the carelessness of the people who are concerned. To strengthen the resistance of the higher elements and to transform the “wild” population of the intestine into a cultured population, these are the means by which the pathological symptoms may be removed from old age, and by which, in all probability, the duration of the life of man may be considerably increased.