PATHOGENIC BACTERIA OUTSIDE THE BODY 221 



and in other countries are transmitted in similar ways. Prob- 

 ably many of the diseases due to spirochetes and trypano- 

 somes are likewise transmitted by necessary insect inter- 

 mediaries. In human medicine the eradication of yellow 

 fever from Panama and Cuba is due to successful warfare 

 against a certain mosquito (Stegomyia) . So ihe freeing of 

 large areas in different parts of the world from malaria 

 follows the destruction of the mosquitoes. The campaign 

 against disease in animals and man from insect sources 

 must be considered as still in its infancy. The full utiliza- 

 tion of tropical lands depends largely on the solution of this 

 problem. 



