12 



of the disease. The time of the dose is important, and the reasons for 

 the time have been abundant!}^ proven b}^ the stud}' of the life of the 

 parasite in the blood cells. 



All of this advice is given only after abundant demonstration of the 

 efficac}' of the methods. These measures have been followed with suc- 

 'cess in the most malarious localities in the world, and with this knowl- 

 edge there is no good reason why an individual should contract malaria 

 in his own home, no matter how much malaria exists around him. 



Fig. 5.— Eggs and larvae of Culex — enlarged (author's illustration). 



Of course, ho irever, there may be occasions where it is almost impos- 

 sible to avoid contracting the disease. For example, last October the 

 writer was waiting for a night train one evening in a small Western 

 town where there were irrigating ditches near the station. In these 

 ditches malarial mosquitoes were breeding profusely, and the insects 

 abounded in the station waiting room and on the platform. Nothing 

 but a gauze covering would have kept them away, and several bites 

 were inflicted on the hands and neck. Fortunately, none of the indi- 

 viduals could have bitten a malarial patient, as the disease was not 

 transmitted. 



TYPHOID FEVER. 



It is not the writer's intention to go further into the causation of 

 this disease than he has already done in his introductorv remarks. He 

 wishes, however, to point out as forcibly as possible the danger of its 

 spread b}' insects and the methods of avoiding this danger. 



House flies and breeding places. — The principal insect agent in this 

 spread is the common house fl}' (fig. 9), and this insect is especially 



