8 



ECONOMIC ZOOLOGY 



allowed out of doors after sunset except they were protected with veils 

 and gloves. Early in the season they were all given doses of quinine 

 to prevent auto-infection. In the unprotected zones no screens were 

 used and everyone was allowed to go without special protection. The 

 result for the summer was that there were no new cases of fever in the 

 protected zone. In the unprotected zones practically all had the fever 

 as usual." 



3. * 



to. 



FIG. 5. Negri bodies or neurocytes hydrophobias, in different stages of chromatic 

 distribution. Greatly magnified. (From Calkins, Protozoology, after Negri.) 



Yellow fever, one of the most dreaded of human diseases is now 

 known to be transmitted by the bite of a mosquito, Stegomyia, just 

 as is malaria by Anopheles. While the germ of the disease has not 

 been seen there are reasons for thinking it may be a sporozoon of 

 extremely minute size, so that a brief account of the disease may be in 

 place here. 



