If attainment of the normal duration of life, which is much greater than the average life to-day, were to overpopulate the earth, a very remote possibility, this could be remedied by lowering the birth-rate. Even at the present time, while the earth is far from being too quickly peopled, artificial limitation of the birth-rate takes place perhaps to an unnecessary extent. It has long been a charge against medicine and hygiene that they tend to weaken the human race. By scientific means unhealthy people, or those with inherited blemishes, have been preserved so that they can give birth to weak offspring. If natural selection were allowed free play, such individuals would perish and make room for others, stronger and better able to live. Haeckel has given the name “medical selection” to this process under which humanity degenerates because of the influence of medical science. It is clear that a valuable existence of great service to humanity is compatible with a feeble constitution and precarious health. Amongst tuberculous people, those with inherited or acquired syphilis, and those with a constitution unbalanced in other ways, that is to say, amongst so-called degenerates, there have been individuals who have had a large share in the advance of the human race. I need only instance the names of Fresnel, Leopardi, Weber, Schumann and Chopin. It does not follow that we ought to cherish diseases and leave to natural selection the duty of preserving the individuals which can resist them. On the other hand, it is indispensable to try to blot out the diseases themselves, and, in particular, the evils of old age, by the methods of hygiene and therapeutics. The theory of medical selection must be given up as contrary to the good of the human race. We must use all our endeavours to allow men to complete their normal course of life, and to make it possible for old men to play their parts as advisers and judges, endowed with their long experience of life. To the question propounded at the beginning of this section of my book, I can make only one answer: Yes, it is useful to prolong human life. II SUGGESTIONS FOR THE PROLONGATION OF LIFE Ancient methods of prolonging human life—Gerokomy—The “immortality draught” of the Taoists—Brown-Séquard’s method—The spermine of Poehl—Dr. Weber’s precepts—Increased duration of life in historical times—Hygienic maxims—Decrease in cutaneous cancer Men of all times have attempted all manner of devices to bring about an increase of years, although they have not considered the problem in its general bearing. In Biblical times it was believed that contact with young girls would rejuvenate and prolong the life of feeble old men. In the first Book of Kings it is related as follows:— “Now King David was old and stricken in years; and they covered him with clothes, but he gat no heat.