55 



Less accurate methods consist in examining the 

 enlarged spleens of the children before and after the opera- 

 tions ; and in noting the decrease of fresh infections in 

 newcomers. For the latter criterion it is, of course, necessary 

 that the newcomers examined have not left the area of 

 operations since their arrival, because otherwise they may 

 have contracted the disease outside. 



The gradual decrease of admissions and attendances for 

 malarial fever in hospitals, especially in the out-patient 

 departments, will be another criterion ; but it will be a good 

 one only if the hospital records have been kept with due 

 care and skill. 



All these tests for the decline of malaria will require the 

 services of medical men and of well-trained medical men. 

 It is always a very difficult matter to form any numerical 

 estimate of the amount of malaria in a given locality, and, 

 consequently, of variations in that amount. In any town 

 where it is proposed to organise mosquito-brigades the 

 laity should be made acquainted with these facts, and 

 should be carefully warned against forming conclusions on 

 hearsay evidence or inexpert opinion. 



In the meantime we may continue our labours in 

 serenity, and with an absolute assurance that the diminu- 

 tion of mosquitoes will ultimately lead to a diminution 

 ot all kinds of mosquito-borne disease. 



It will be scarcely more easy to gauge the decrease in 

 the number of mosquitoes than to gauge that of malaria. 

 Perhaps the best plan will be to employ the mosquito trap 

 described on page 11. Persons should be induced to sleep 

 nightly at different spots in mosquito-nets with several 



