12 THE BUREAU OF SCIENCE 



INVESTIGATION 



So much of the time of the staff has of necessity been required 

 for routine examinations that only one man has been regularly 

 engaged in research work. Nevertheless considerable important 

 work has been accomplished. 



Every piece of research that is intelligently chosen and is 

 prosecuted by a capable investigator must contribute to our 

 scientific knowledge. Although the practical importance of the 

 results as measured by pesos or human lives may not be imme- 

 diately apparent, they may later prove to be of vast benefit to 

 mankind. The discovery by Theobald Smith in 1892 that Texas 

 tick fever was transmitted by the bite of the cattle tick may 

 not have appeared at that time to be of great practical im- 

 portance ; yet it disclosed the principle of the insect transmission 

 of tropical diseases, which has enabled medical science to control 

 malaria, yellow fever, and other diseases, and has rendered 

 possible the construction of the Panama Canal, which had failed 

 previously on account of the great mortality from these diseases 

 in the Canal Zone. 



All of the enumerated researches carried on in the biological 

 laboratory during the period covered by this report have prac- 

 tical results which are immediately apparent. Investigations in 

 progress include the following : 



Cholei^a. — An interesting series of studies as to the viability 

 of B. cholerse in water under ordinary conditions of light and 

 temperature is being carried on. Another investigation deals 

 with the irritability of the cholera bacillus under certain con- 

 ditions. 



Malaria. — An experimental determination of the distribution 

 and the species of the mosquitoes capable of transmitting malaria 

 in the Philippines is in progress. Several species have been 

 definitely identified as "carriers," and the result of this work 

 will contribute greatly to the sanitary improvement of these 

 Islands, and will afford a great financial saving in any campaign 

 against malaria. The health authorities of the Canal Zone es- 

 timated that from $150,000 to $200,000 were saved in their 

 malaria campaign by the discovery that a certain anopheles 

 mosquito that bred in the hollows of rotten stumps could not 

 transmit malaria. 



Tuberculosis. — Experiments on tuberculosis which were pre- 

 viously reported have been continued. 



Leprosy. — The investigation on leprosy previously reported 

 is still being carried on, and studies on the cultivation of B. lepne 



