CONSERVATION OF HUMAN ENERGY. 411 



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 at- 

 tained. 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 main- 

 tain 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 atten- 

 tion 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 



