578 



Yellow Fever 



3. An interval of about twelve days or more after con- 

 tamination appears to be necessary before the mosquito is 

 capable of conveying the infection. 



Fig. 200. Stegomyia fasciata (Stegomyia calopus): a, female; b, male 

 (after Carroll) . 



4. The bite of the mosquito at an earlier period after 

 contamination does not appear to confer any immunity 

 against a subsequent attack. 



