July 7, 1916] 



SCIENCE 



33 



The amount of retrogression in the expecta- 

 tion of life of the males rarely exceeds half of 

 a year, but the mere fact that individuals at 

 ages above fifty do not live as long now as 

 they did several decades ago is of tremendous 

 significance. If this period or retrogression 

 could be made to vanish, so much more would 

 the expectation of life at the earlier ages be 

 increased. It would be serious enough if no 

 advance were registered in this period; an 

 actual retrogression amounts to a calamity. 



It is very remarkable that the period of re- 

 trogression of the males in the decade 1900- 

 1910 ends about age sixty-five and from that 

 age on we notice a tendency to " come back," 

 a tendency not found in the decade 1890-1900. 

 The value of this " come back " is small, it is 

 true, but the values give no indications of un- 

 certainty by interposing occasionally a nega- 

 tive value (a retrogression). Whether this 

 period of advance at the most extreme ages 

 actually exists or not, we shall not presume to 

 say, but the above figures are highly suggest- 

 ive. 



The period of retrogression among the ex- 

 pectations of life of the females also begins 

 about age fifty, but there is quite a difference 

 between the two decades considered. In the 

 decade 1900-1910 the females seem to have 

 overcome to a great extent the retrogression 

 registered in the decade 1890-1900 ; this fact is 

 not true of the males. Moreover, this period 

 is now restricted to only about twenty years, 

 whereas before it seemed to extend firmly to 

 the end of the table. 



Here again, we see evidences of an effort to 

 " come back " appearing at the extreme ages. 

 The fact that this period of " come back " ap- 

 pears among the expectations of life of the 

 females in the same decade (1900-1910) as it 

 does among the males adds strength to the 

 probability of its actual existence. 



The casual reader may have wondered how 

 the period of retrogression among the death 

 rates could extend to the end of the table 

 while that of the corresponding expectations 

 of life could end at some age such as 75. This 

 is perfectly possible, for in obtaining the ex- 



pectation of life at any age we divide the total 

 number of years lived, by the population at 

 that age, and this total number of years may 

 be lessened without decreasing the expectation 

 of life if the population at the given age is also 

 lessened in the proper proportion. 



In this paper we have pointed out a great 

 field for work; we have pointed out the exact 

 location of a serious problem. It still remains 

 for others to diagnose the trouble, and that 

 task might well be left to those familiar with 

 the diseases operative at the ages covered by 

 this period of retrogression. However, we 

 dare suggest that far the greater part of the 

 trouble is due to a peculiar state of indiffer- 

 ence and ignorance in regard to the ordinary 

 laws of nature, and therefore can be overcome 

 best by a systematic plan of education along 

 lines of elementary hygiene. 



Every one knows that few individuals be- 

 tween the ages of thirty and sixty take any 

 constructive forethought for their physical 

 welfare; few carry out any definite plans for 

 regular daily exercise or proper breathing of 

 fresh air. Fewer still have even a fair con- 

 ception of their own physical make-up or their 

 condition at any particular time; this fact is 

 due likely both to lack of time and to reluc- 

 tance to face the truth. 



One of the best ways to arouse interest in 

 practical hygiene would be through the organi- 

 zation of a National Health League which 

 would hope ultimately to have a representa- 

 tive organization in every large community. 

 It should be the duty of such a body to encour- 

 age right living among its members and all 

 individuals associated with them. This work 

 should be supplemented by a systematic and 

 regular program of study and discussion. For 

 local organizations made up of individuals who 

 insist they are too busy to make a personal 

 study of the subject, practical lectures could 

 be arranged at regular intervals, calculated to 

 keep interest aroused. The lecturers could be 

 obtained among broadminded and altruistic 

 physicians or the faculty of the state univer- 

 sity. The central organization, whether state 

 or national could employ a part of its time and 

 energy in no better way than in providing 



