THE HABITS AND HISTORY OF CENTENARIAN'S. 623 



teeth, some had been without them many years, and the average num- 

 ber retained was only four or five, which, in many instances, we may 

 conclude to have been of little value. The artificial substitutes were 

 used in so few instances, that we can not from them form an estimate 

 of the aid afforded by these appliances in the prolongation of life ; 

 but that they do contribute to the maintenance of health and the pro- 

 longation of life can scarcely be a matter of doubt. The teeth had dis- 

 appeared, as we have before found to be the case (" British Medical 

 Journal," May 9, 1885, page 929) in the upper jaw more than in the 

 lower ; but the tables do not show so much difference between the 

 men and the women as I then marked. 



It is somewhat remarkable that, though as many as twenty-eight 

 used glasses, thirty-five, including many who used glasses, are reported 

 to have been in the enjoyment of good sight. The occurrence of 

 presbyopia does not seem to be associated with, or to be a prelude to, 

 inconvenience or impairment of sight beyond that which may be cor- 

 rected by glasses. These had been used by some for forty or fifty years ; 

 and in three it appears that the defect was spontaneously rectified, and 

 that as they grew older they became able to dispense with glasses. 



That the majority of centenarians are content, as we find them to 

 be, with three meals in the day, and are moderate or small eaters, par- 

 taking of little animal food and little alcohol, is in harmony with the 

 lowered activity of the muscular and other organs, and the conse- 

 quent lowered demand upon the nutritive processes and the nutritive 

 supply. That nevertheless the rate of the pulse, averaging TO, and 

 that of the respiration, averaging 22, is maintained, may be accounted 

 for by the diminished elasticity of the circulatory and respiratory 

 apparatus. The arteries become less capable of accelerating the blood- 

 stream, and the vital capacity of the chest is much reduced, as shown 

 by the slight difference in the chest-girth between the state of inspira- 

 tion and that of expiration. 



The sleep-duration, averaging nearly nine hours, indicates also a 

 slowness, a feebleness, of the restorative processes. Repair is tardily 

 and with difficulty striving to keep pace with wear. AVe know that it 

 is one element in the developmental law of growth and decay, that it 

 should not quite do so in the aged frame. Up to adolescence repair has 

 the mastery, and the body gains in weight and strength ; in middle 

 age, repair is about equal to wear ; but in later life its gradual failure, 

 attended with diminishing weight and strength, conducts the body 

 slowly along its normal course to dissolution. Long, good sleep, does 

 something to put a drag on the downward course, and is a great sus- 

 tainer of the aged frame. Much difference in sleep-duration is noted 

 in the tables. In some, sleep is said to have been short and indifferent, 

 or bad, perhaps owing to peculiar disturbing causes ; but in 32 out of 

 4i it is said to have been good. 



The maladies of these old people range themselves chiefly under 



