November 18, 1904.] 



SCIENCE. 



665 



against the bite of Anopheles. It is ob- 

 vious that this plan may often be diffi- 

 cult of execution because of the impossi- 

 bility of exercising efficient control over the 

 movements of individuals suffering from 

 latent or recurrent infection. 



A second possibility consists in the gen- 

 eral protection against mosquito bite of all 

 persons dwelling in infected regions. The 

 pestiferous insect may beat its wings in 

 vain against the windows of a mosquito- 

 proof dwelling; if it can not come near 

 enough to the human being to inject the 

 contents of its poisoned salivary gland, no 

 single ease of malaria will result. In parts 

 of Italy, it is said, this mode of prevention 

 has been practised with brilliant success in 

 protecting railway employees, forced by 

 the exigencies of their calling, to reside in 

 highly malarious localities. 



A third point of attack is presented in the 

 possibility of destroying or at least arrest- 

 ing the propagation of the insect host of the 

 malarial parasite. The extermination of 

 a number of species belonging to a widely 

 distributed and abundant insect genus may 

 seem in itself a gigantic task to undertake. 

 Remembering the ambiguous success that 

 has attended the eiforts of the human race 

 to combat the ravages of certain insects in- 

 jurious to agriculture, it is not easy to be 

 sanguine concerning the speedy extinction 

 of Anopheles. It is noteworthy that the 

 most considerable triumphs attained along 

 economic lines have been effected by the 

 utilization of the natural enemies of the 

 noxious forms. Efficient foes of Anopheles 

 have so far not been discovered. There is 

 no question, however, that in definite local- 

 ities the number of individual mosqui- 

 toes belonging to malaria-bearing species 

 may be enormously diminished by the de- 

 struction of the breeding-pools. The la- 

 bors in this direction of English health 

 officials in various parts of the world have 



been rewarded by a decisive decrease in the 

 prevalence of malaria. 



It will not escape remark that the effect 

 of any one or of all of these protective 

 measures is cumulative. A diminution in 

 the number of mosquitoes, or in the num- 

 ber of persons harboring the malarial pro- 

 tozoon in their blood, or in the number of 

 infected or non-infected individuals bitten 

 by mosquitoes, will inevitably produce a 

 lessening in the amount of malaria in a 

 given region. This will in turn diminish 

 the opportunities for mosquitoes to become 

 infected and will at least put a check upon 

 indefinite extension of the disease. It is 

 significant that a high degree of success 

 apparently attends the enthusiastic and 

 persistent application of any one of the 

 measures above instanced. 



While malaria, typhoid fever and tuber- 

 culosis are to-day fairly in the field of 

 view of public hygiene, such is not the case 

 with a host of other maladies. A begin- 

 ning is made here and there, but the vast 

 majority of the diseases that affect man- 

 kind still lack an intelligent and organ- 

 ized opposition. This is partly because of 

 insufficient knowledge. At the present time 

 the apparent increase in pneumonia pre- 

 sents an imperative field for research. It 

 seems unlikely that the available modes of 

 attacking this disease are to be exhausted 

 with attempts to improve individual pro- 

 phylaxis. A clear understanding of the 

 tangled web of statistical, climatic, racial, 

 bacteriological and hygienic questions that 

 environ this urgent problem of public hy- 

 giene is likely to come only through re- 

 newed investigation of the phenomena. If 

 it is true, as some conjecture on what 

 seems insufficient evidence, that the viru- 

 lence of the pneumococeus is increasing, 

 what is the bacteriological strategy suited 

 to the emergency? Or if it turn out that 

 an increase in the number of victims to 

 pneumonia is largely made up of those who 



