OF WASHINGTON, VOLUME XIV, 1912. 81 



Dr. Howard called attention to the paper by Dr. Lutz 

 of Brazil, on forest mosquitoes and forest malaria, which 

 appeared to contradict Mr. Knab's statements. 



Mr. Knab replied that he had just discussed this paper 

 from his present viewpoint with Dr. Dyar. They had reached 

 the conclusion that Dr. Lutz had misinterpreted the facts. 

 Dr. Lutz's observations were made in the state of Sao Paulo 

 during the construction of the railroad from the coast to the 

 capital. The first part of the route was through the moist 

 and heavily forested slope from the table-land to the coast, 

 and while at work here a large part of the laborers were af- 

 flicted with malaria. Lutz searched for the transmitting 

 Anopheles, but could find no breeding-places upon the steep 

 slopes. Finally he determined that a single species of Anoph- 

 eles (cruzii] was abundant in the region and that this bred 

 in the water of epiphytic bromeliads. To this species he at- 

 tributed the outbreak of malaria. It would seem now that 

 the Anopheles found by Dr. Lutz probably had nothing to 

 do with the outbreak of malaria among the construction 

 gang. It is a well-known fact that in the tropics most persons 

 apparently in good health have latent malaria. When such 

 an individual comes under some physical strain, such as 

 overexertion, fatigue, or exposure, the disease manifests itself. 

 It therefore seems highly probable that the men observed by 

 Lutz already harbored malaria in a latent form when they 

 came into the region and that the exertion and exposure 

 incident to the work caused the irruption of the disease. 



Mr. Busck stated that he had investigated the mosquitoes 

 of the upper Chagres in 1907 and could confirm Mr. Knab's 

 statements with reference to Anopheles albimanus. He found 

 that on the uninhabited parts of the Chagres Anopheles eiseni 

 was the prevalent species, while A. albimanus was not found 

 by him there, and this absence was not due to lack of breeding 

 facilities. He expressed the opinion that at points still farther 

 up on the Chagres, where there are settlements, at San Juan 

 for example, .1. albimanus would be found. 



