THE CONSERVATION OF ENERGY. 543 



This is particularly true of underwear, which should be light and porous, 

 preferably linen next to the skin, which can be supplemented by extra 

 woolen underwear placed over this to vary with the conditions of the 

 temperature. Outings are essential to encourage free oxygenation 

 through the lungs and the skin. Chill of surface is much more likely 

 to follow exertion where too much or too heavy underwear is used, and 

 the results are far more serious than if there is too little. If the skin 

 be leaky, becoming readily moist on exertion, excessive precaution must 

 be used lest secondary chill follow. If the underwear is made damp 

 by exercise, it is important to change this as soon as possible and 

 whenever it is produced. Above all the foot gear should be frequently 

 changed to secure airing of these over-clothed members. 



The most important specific recommendations I wish to offer for 

 the postponement of the degenerative effects of age and for the recovery 

 of so much of the normal vigor as is possible in each have to do with 

 the forms and qualities of the exercises. As has been shown, the 

 tendency of the tissues in advancing age is toward a steady and irre- 

 trievable hardening or stiffening or loss of elasticity, due to normal or 

 abnormal increase in the connective tissue. The results of these changes 

 are seen not only in the rigidity of the spinal column and ligaments, 

 the skin, the muscle sheaths, the structures of the blood vessels, the 

 connective tissue framework of the great organs, etc., which are obvious 

 enough, but the really disastrous effects are those brought about by 

 this xerosis upon the organs concerned in the processes of nutrition 

 and of the special senses. This point I do not see brought out in any 

 literature which has met my eye. Let me illustrate this. We have, 

 as age creeps on, a loss in cellular activity in the functions of the special 

 senses, well shown for example in dimness of vision, loss of hearing 

 and slowness of cerebration. Much of this is inevitable and must 

 continue. Some of this, however, can be delayed almost indefinitely. 

 It will be observed that the tissues about the neck of an old person 

 exhibit conspicuous loss of elasticity, so much that oftentimes dense 

 rigidities are present, especially marked in the nuchal region. 



I have been surprised and gratified to find that regulated move- 

 ments of the neck and upper truncal muscles, employed for the pur- 

 pose of accomplishing something else, resulted in a conspicuous im- 

 provement in hearing, in vision, in cerebration and, as a consequence of 

 a betterment in cerebral circulation, also in sleep. Following this 

 thought I have repeatedly been able to promise, and fulfil the promise, 

 that an individual who had suffered impairment in these particulars 

 should enjoy distinct improvement in the function of sense organs by 

 employing regulated movements. 



What is true of these structures is equally true of the abdominal 

 viscera. A large proportion of the digestive disturbances, even of those 

 in earlier middle life, are due to a relaxation in the supporting tissues 



