On the day that we began to pen these lines we were congratulating one of the multifarious professors of the medical faculty of Berlin on his 73d birthday. He is in perfect and robust health, and is at present engaged on the third edition of his work, which is well known in medical circles all over the world. He told us his father was 33 and his mother 48 when they died, and several of his brothers died before reaching old age. However, his grandfather lived to be 90. This savant has always led a sober and regular life. Sometimes chronic diseases, like syphilis, etc., do not prevent people who come from a long-lived family from attaining to a very old age. Thus a patient of mine, a French gentleman of 72 years, who still shows symptoms of the tertiary form of syphilis acquired fifty-two years ago, is still looking in splendid health, like a man of 60, and was complaining to me about his too strong sexual feelings. Likewise, the father of a patient of mine has reached his 96th year in spite of his syphilis, which he acquired an age ago. If we now consider the environments where the longest-lived persons are found, we shall find that those who always live in the open air, and also moderately, rising early in the morning and leading day by day the same regular life, have attained the longest lives. A great number of long-lived patriarchs can be found among the peasants, or at least among persons living in the country and out in the fresh air all day. Undoubtedly the greatest number of long-lived people are to be found in the British Islands, especially in Scotland. The inhabitants of Great Britain are well known to appreciate fresh air, and on the Continent we often see them, especially Scotchmen, going about without any overcoat even on a cold winter’s day. We shall see in various chapters of this book how essentially important is a sound hygiene to ensure long life, and we shall demonstrate in separate chapters the great importance of fresh air and of exercise in the open air. If we would inquire where are to be found the greatest number of persons over 100 years of age, the palm must be given to Bulgaria, if what is claimed be true, _viz._, that there are 3800 persons over that age, and all these folk partake daily of “jogurth,” a sour milk containing three different microbes, the most efficacious among them being the maeja bacillus. In Germany, with its 61,000,000 of inhabitants, there are but 71 persons over 100 years old, while Bulgaria, with only 7,000,000, claims to have 3800, and that it is due to the jogurth eaten every day. We will deal more fully with jogurth in the chapter on the elimination of toxic products from the intestines. ------------------------------------------------------------------------ CHAPTER VII. ON MEANS WHICH CAN HELP US TO DETERMINE THE PROBABLE DURATION OF LIFE.