Although he is a recent arrival on the earth, man has already made great progress, as compared with his ancestors the anthropoid apes, and we learn the same if we compare the higher and lower races of mankind. Yet there remain many disharmonies in the organisation of man, as, for instance, in his digestive system. A simple instance of this kind is furnished by the wisdom teeth. The complete absence of all four wisdom teeth has no influence on mastication, and their presence is very frequently the source of illness and danger. In man they are indeed rudimentary organs, providing another proof of our simian origin. The vermiform appendix, so frequently the cause of illness and death, is another rudimentary organ in the human body, together with the part of the digestive canal to which it is attached. The organ is a very old part of the constitution of mammals, and it is because it has been preserved long after its function has disappeared that we find it occurring in the body of man. I believe that not only the appendix, but a very large part of the alimentary canal is superfluous, and worse than superfluous. It is, of course, of great importance to the horse, the rabbit, and some other mammals that live exclusively on grain and herbage. The latter part of the alimentary canal, however, must be regarded as one of the organs possessed by man and yet harmful to his health and life. It is the cause of a series of misfortunes. The human stomach also is of little value, and can easily be dispensed with, as surgery has proved. It is because we inherit our alimentary canal from creatures of different dietetic habits that it is impossible for us to take our nutriment in the most perfect form. If we were only to eat substances that could be almost completely absorbed, serious complications would be produced. A satisfactory system of diet has to make allowance for this, and in consequence of the structure of the alimentary canal has to include in the food bulky and indigestible materials, such as vegetables. Lastly, it may be noted that the instinct of appetite in man is largely aberrant. The widespread results of alcoholism show plainly the prevalent existence in man of a want of harmony between the instinct for choosing food and the instinct of preservation. Far stronger than the social instinct, and far older, is the love of life and the instinct of self-preservation. Devices for the protection of life were developed long before the evolution of mankind, and it is quite certain that animals, even those highest in the scale of life, are unconscious of the inevitability of death and the ultimate fate of all living things. This knowledge is a human acquisition. It has long been recognised that the old attach a higher value to life than do the young. The instinctive love of life and fear of death are of importance in the study of human nature, impossible to over-estimate.