Metchnikoff, one of the most intrepid students of life of our time, has boldly declared that the appendix, the caecum and the whole of the great bowel—a massive and long tube with a highly-organized system of coats and tissues and vessels—are useless structures in the body of man. Nay, under certain conditions, the presence of the colic system may be a constant danger to life. Such a statement, coming from a biologist of the very first rank, is bound to carry authority and persuasion. If Metchnikoff's opinion is well founded then the colic system of man is a gigantic blunder in animal construction. We have always supposed that Nature made no mistakes.
The evidence in support of Professor Metchnikoff's theory is altogether unconvincing. We have not yet discovered the function of the various parts of the great bowel—the appendix, caecum and colon. It has always been the custom to regard those organs whose functions or uses are unknown as useless, rudimentary or vestigial organs. As our knowledge of the body has increased the list of useless organs has decreased. Our knowledge of the human colic system is of the crudest. The function of the appendix we do not know, but in the human body at birth it is identical in form and structure to the appendix of the great anthropoids. It is when boyhood and girlhood are reached that it becomes liable to disease and to undergo reduction in size and contortion in shape.
We seem to be dealing with a change in structure of exactly similar nature to those degenerative changes which we have already noted in the teeth, jaws and throat. In their case it seemed most likely that their change in form is a result of diet and it seems very probable that the same statement will yet be proved to be true in the case of the appendix.
What little we know of the function of the colon favours the opinion—for our knowledge as yet is only a collection of opinions founded on a few facts—that the fault lies not in the colic system but in the nature of the work it is asked to perform in modern man. Its main work in our ancestors consisted in the digestion of the cellulose or husk elements of grains and of fruit and vegetables. Our modern dietary has called upon it to act upon a dietary totally different to that for which it was evolved. Should we then blame the colon and call it a useless structure ?
Metchnikoff has helped us to understand the rich fauna of micro-organisms which flourishes within the colon. Under normal circumstances the bacteria appear to assist in colic digestion; nay, it is possible they are essential factors in colic digestion. We cannot conceive that the fauna which flourished in the colon of Neolithic man will thrive under the conditions which hold in modern man. Injurious forms of fermentations do occur within the great bowel of civilized races.
Absorption of fluids takes place from the colon. It is in the colon that the faeces assume their solid form. It is probably when the contents are injuriously changed by fermentation that substances are absorbed which poison the whole system. In cases where such pathological conditions prevail the surgeon will relieve a patient's condition by either removing the colon altogether or by performing an operation which will throw it out of action. If relief is thus obtained we must not infer that the colon is a useless organ ; all that can be said is that it is not indispensable to modern man living on a highly artificial diet. There are a very few parts of the body which the surgeon has not removed when their removal is necessitated by disease. Because a man can get along in life with only one arm or one eye we must not suppose that the second arm or the second eye were superfluous. There is another important fact known to all biologists; in the alimentary system of every vertebrate animal a part is specialized to serve the purpose of a colon. It is not likely that such an ancient and essential part of the animal body should suddenly become useless. The evidence, so far as it goes, leads one to think that the kind of food and the nature of cooking now used by highly civilized races are unsuitable for our alimentary systems. We can hardly expect evolutionary processes to keep pace with our pampered and often extravagant appetites. As rational beings we should try to adapt our diet to the colon rather than expect that structure to adapt itself to our diet. Still, whatever the cause and the cure may be there can be no doubt that certain parts of our alimentary systems are out of harmony with their modern surroundings.
As regards the other systems of the body, the brain and nervous system, the muscles and bones, the writer is not aware of any modern change which can be detected in them, with one exception. The long bones of the lower limbs appear to be altering in form. In the thigh-bones of the early British, as late as the date of the Anglo-Saxon invasion, there is a peculiar flattening of the upper end of the femur. The leg-bone or tibia of these is often flattened from side to side, giving it a sword-like shape. Thigh and leg-bones of this type are uncommon in our modern population. The meaning of the change in femur and tibia we do not understand. Some have attributed these ancient characters to the habit of squatting; others have supposed them to indicate a people who were accustomed to hill climbing.
Thus it will be seen that there is no symptom of bodily decay in modern man if we except —and they are important exceptions—those of the alimentary system. The so-called signs or stigmata of criminalism have already been briefly alluded to in connexion with the outer ear.
The specialization of modern life does compel men and women to spend their lives under conditions which are ill-suited for maintaining the body in a state of fitness and health. The growing body cannot develop normally unless the muscular system is regularly and naturally exercised. At no time has physical culture been more widely popular than at present. It has effected much that is good and perhaps a little that is really harmful. We see modern methods of physical culture replacing the exercises of the drill-sergeant of a past generation. The ideal human body, in the opinion of the old drill-sergeant, was that of a man at attention, with head thrown abnormally back, pouting, expanded chest, enclosed within a tightly-fitting tunic, back rigid, muscles tight and brawny, toes turned outwards. That was his ideal, and it was wonderful how he succeeded in turning raw recruits into these parade soldiers. The ideal of course was wrong ; agility, health and endurance were sacrificed to parade effect. The ideal, too, which is the aim of so many modern " professors " of physical culture is equally wrong. They aim at producing a voluminous chest and a Herculean musculature. They cultivate in their pupils a muscle system which would fit them to earn their livelihood as navvies. Such an over-development, we shall see, is always bought at a price.