These exercises should be along the normal functional lines, not out of them, but keeping in view the fullest range of customary movements, many of which become impaired and almost lost from lack of accurate use even in young persons. First of all, bear in mind that nine tenths of ordinary movements of the arms are flexions, hence it is necessary, in order that one may become symmetrically developed to practise forceful, accurate extensions till complete extensor competence is attained. The movements of the legs are mostly extensions, hence in them flexions must be cultivated systematically.
In the motor areas of the brain there are probably two sets of cells coexisting alongside, one for flexions, and one for extensions. In the arm centers those for flexions are in constant use, hence well developed, and the extensor cells suffer degenerative change. In the center for the legs the reverse obtains. The neck and structures about the shoulder blades in man are little used in the ordinary demands of life, where few movements are called for, and hence are seldom brought into full action. These readily become rigid from disuse and fail to maintain symmetry. Yet in this region lie some of the most important subsidiary nerve centers. The effects of these rigidities by exerting pressure on nerves and blood vessels impair nervous mechanisms, and hence the nutrition of the organs of special sense in the head suffer. As these are removed dimness of vision grows less, hearing more acute, discomforts or pains in the head cease, and youthful capacities and bienfaisance are in great measure restored.
Unless these tissues are kept mobile, especially at the age when free activities are gradually abandoned, this region loses beauty rapidly and nowhere is the evidence of age more conspicuous.
Diet, already alluded to, exerts a most influential bearing on health, and hence comeliness. It is enough to offer here a brief summary of the guiding principles of dietetics which will suffice for all ordinary exigencies. A word must be said about the care of the teeth upon which often the whole proposition depends. Teeth receive good attention by nearly all civilized people to-day, yet we physicians are often amazed at the instances of neglect which fall under our observation. Many of these dental defects prove to be the chief factor in obscure conditions of deplorable ill health, even among people of wealth and refinement. This is especially true of disorders of the gums.
In order to maintain digestive competence, from intake to output, it makes far less difference what food is eaten, than the manner of taking, and the amounts consumed. In the choice of foods, a good rule for most people is to make a selection from those articles which are ordinarily accessible and eat with contentment and thankfulness, being guided by a purely natural appetite. Artificial environment and faulty upbringing tend to impair the sanity of taste and appetite, and