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SCIENCE. 



[N. S. Vol. XIV. No. 358. 



widening streets for the purpose of supplying 

 more air and light to habitations, better meth- 

 ods for the collection and removal of the wastes 

 of human life, improvement in connection with 

 infant and orphan asylums and in the manage- 

 ment of schools and prisons. 



The nineteenth century can boast of many 

 advances in hygiene, particularly since the 

 European invasion of cholera in 1830. English 

 towns which had been visited by this disease, 

 and those fearing similar scourges, freely insti- 

 tuted sanitary reform in the establishment of 

 sewers, public water supply, sanitary homes 

 for wage-earners, etc., but even during the 

 Crimean War, the medical officers of the army 

 evinced a shameful ignorance of the principles 

 of sanitation and induced Edmund A. Parkes 

 to write his manual of Practical Hygiene, and 

 his teachings have borne ample fruit, especially 

 in the improvement of the air we breathe and 

 the water we drink. The question, has human 

 suffering been mitigated and human life greatly 

 prolonged by efforts in sanitation, can be em- 

 phatically answered in the affirmative. The 

 average length of human life in the sixteenth 

 century was only between 18 and 20 years ; at 

 the close of the eighteenth, it was a little over 

 30 years, while to-day it is over 40 years. In- 

 deed, the span of life since 1880 has been length- 

 ened about six years, as shown by statistics in 

 Mul hall's Dictionary of Statistics (4th Edition, 

 London, 1899). Mr. William A. King, Chief 

 Statistician in the U. S. Census Office, informs 

 the writer that from the results of the mortality 

 returns for the twelfth census, for the States in 

 which the returns were secured from registra- 

 tion records in both 1890 and 1900, there ap- 

 pears to be an absolute decrease in the general 

 death rate of about 1.8 per 1,000 of population. 

 This decrease seems to be most marked in the 

 rate due to scarlet fever, whooping cough, 

 diphtheria and croup (combined), typhoid fever, 

 malarial fever, consumption, diarrheal diseases 

 and diseases of the nervous system, the de- 

 crease in the mortality in diphtheria and croup 

 amounting to more than 50 per cent. On the 

 other hand, the rate due to cancer and tumor 

 (combined), Bright's disease, heart disease and 

 dropsy (combined) and pneumonia is appa- 

 rently greater than in 1890, the increase be- 



ing most marked in the case of Bright's disease, 

 cancer and tumor and pneumonia. The results 

 in the decreased rate of diphtheria, croup, 

 scarlet fever, typhoid fever, whooping cough, 

 consumption, malarial fever and diarrheal dis- 

 eases are the direct outcome of preventive 

 medicine and are as gratifying as they are 

 striking. We note with regret the increased 

 rate in Bright's disease, heart disease, dropsy 

 and pneumonia, and may well pause to inquire 

 whether our ever-increasing annual * national 

 drink bill,' averaging 17.68 gallons per capita, 

 may not be a factor in the development of these 

 diseases, especially since there is reason to be- 

 lieve that the habitual and immoderate use of 

 alcohol, apart from increasing the connective 

 tissue and causing cirrhosis, also produces fatty 

 degeneration, especially of the heart, liver and 

 arterial coats, probably because it promotes the 

 conversion of albuminoids into fats. Since our 

 knowledge of the nature of infectious diseases 

 has been more and more defined, scientific 

 methods for their prevention have been applied. 

 We have learned, too, that in addition to the 

 germ there must be a suitable soil for its pro- 

 liferation, and that sanitation will not only de- 

 stroy the environments for its development 

 without the body, but also place the system in 

 the best possible condition to resist its toxic 

 action. The application of this knowledge has 

 saved millions of lives, besides an incalculable 

 amount of human suffering and distress, not to 

 mention the economic aspect of the question. 

 When we remember all this and the fact that 

 Jenner's discovery, at the close of last century, 

 of a fundamental and practical method of pro- 

 ducing artificial immunity has been far eclipsed 

 in the last 20 years, and that we possess to-day 

 not only curative but also protective sera for 

 diphtheria, erysipelas, tetanus, plague and pos- 

 sibly cholera, tuberculosis, typhoid fever, pneu- 

 monia and a number of other immunizing agents 

 for diseases of man and the lower animals, we 

 have reason to believe that the solution of the 

 problem of immunity is only a question of time 

 and we may indeed expect great possibilities in 

 our battle against infectious diseases. Great as 

 our progress has been, much remains to be done. 

 While every scientific physicia,n familiar with 

 biological research knows full well that if the 



