Report of the President 83 



of mosquitoes by oil and by predaceous fish are illustrated. 

 Among the additions to this exhibit are an oil-painting of 

 Camp Lazear, where American Army surgeons demonstrated 

 the mosquito theory of yellow fever, and a photograph of 

 General Gorgas, who so effectively put this theory to the test 

 at Cuba and at Panama. 



The most important single addition to the Hall of Public 

 Health during the year is a remarkably detailed and accurate 

 model of the body louse, the carrier of typhus fever. This 

 model is 100 times the length of the insect and was prepared 

 from the study and comparison of many hundreds of speci- 

 mens by Mr. Ignaz Matausch, who donated it to the Museum. 



A colored frieze, illustrating the clouds as the original 

 source of water supply, the storage of water in lakes and its 

 history as it flows down through smaller and then larger 

 streams, has been prepared by Mr. A. Operti for the portion 

 of the hall occupied by the exhibits of water supply sanitation. 



The work of the Museum of Living Bacteria was supported 



during the early part of the year by special gifts from Mr. 



. , . ,„ Felix M. Warburg and Dr. Walter B. 



Bacteriological Museum , 



James. Ihe assistance thus rendered 



at a critical period made possible the continuance of this 

 unique service, which the Museum renders to hundreds of 

 institutions of learning all over the world, a service which the 

 disorganization of scientific work in Europe has rendered of 

 peculiar importance. The income from the Morris K. Jesup 

 Fund has finally made it possible to place the work of this 

 laboratory on a more permanent basis and to employ a much- 

 needed additional laboratory assistant. 



The laboratory now has 695 different strains of bacteria 

 under cultivation. Newly discovered organisms like those 

 having causal relation to typhus fever and to common colds 

 are being constantly added to the collection. During the 

 year ending December 1, 1915, 3,404 cultures were sent out 

 without charge to laboratories of universities and health 

 departments, making a total of 11,216 cultures distributed 

 since the opening of the laboratory. More than 408 different 

 institutions have benefited by this service. 



