114 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



food-supply in man and animals. I do not think that this differ- 

 ence is explainable by topographic conditions, but I believe that 

 where conditions are otherwise favorable it is governed by the con- 

 sideration just mentioned. 



Finally it must be admitted that, in formulating what I believe 

 to be an important principle, I have been somewhat dogmatic. But 

 the nature of the subject, and, except in the case of the most pro- 

 nounced examples, the dearth of observations bearing upon it, have 

 made this necessary. If I have caused students to think, to criti- 

 cise, and perhaps to investigate from a new point of view, I shall 

 feel that I have done something worth while. 



-In connection with the foregoing papers Dr. Dyar made the 

 following remarks : "To state the matter concisely, certain workmen 

 engaged in railroad construction in a wild, wooded country, were 

 afflicted with malaria. Dr. Lutz, investigating the outbreak, found 

 no other Anopheles present but the species breeding in the epiphytic 

 bromeliads in the forest, A. lutzii Theob. He concluded that they 

 were responsible for the outbreak of the disease among the workmen. 



At the time of his investigation, it was not known to what a de- 

 gree of specialization the malarial relation had established itself. 

 It was thought that malaria in man was to be considered as con- 

 veyed by Anopheles as against other mosquitoes. Lutz's conclusion 

 was, therefore, at the time a natural and plausible one. But we now 

 know that the malarial relation is a highly specialized one. Each 

 kind of malaria is conveyed usually by but one or two species of 

 Anopheles in a locality. Often we have in a given locality several 

 species of Anopheles present, only one of which is capable of carry- 

 ing the form of malaria prevalent there. Mr. Knab has pointed out 

 that for such a delicate relation to have established itself, an habit- 

 ual association of the vertebrate host and mosquito host must 

 have preceded; in other words domestic or semidomestic Anopheles 

 only will be found to be malaria carriers. This view renders Dr. 

 Lutz's conclusion less plausible than when viewed in the former light, 

 and, in conversation with Mr. Knab, we had concluded that Dr. 

 Lutz's explanation was probably erroneous. Certainly, in view 

 of recent discoveries, Dr. Lutz's explanation is at least unlikely 

 and unusual and can be accepted only after strict proof. 



It seems to me that there are three possible theories to account 

 for the outbreak of malaria observed by Dr. Lutz. First, that the 

 true carrier was overlooked. Second, that the disease was spread 



