3I0SQUIT0ES AND YELLOW FEVER 129 



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. 



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

 contamination does not appear to confer any immunity 

 against a subsequent attack. 



5. Yellow fever can also be experimentally produced 

 by the subcutaneous injection of blood taken from the 

 general circulation during the first and second days of 

 this disease. 



6. An attack of yellow fever, jDroduced by the bite of the 

 mosquito, confers immunity against the subsequent injec- 

 tion of the blood of an individual suffering from the 

 non-experimental form of this disease. 



7. The period of incubation in thirteen cases of experi- 

 mental yellow fever has varied from forty -one hours to 

 five days and seventeen hours. 



8. Yellow fever is not conveyed by fomites, and hence 

 disinfection of articles of clothing, bedding, or merchan- 

 dise, supposedly contaminated by contact with those sick 

 with this disease, is unnecessary. 



9. A house may be said to be infected with yellow fever 

 only when there are present within its walls contami- 

 nated mosquitoes capable of conveying the parasite of 

 this disease. 



10. The spread of yellow fever can be most effectually 

 controlled by measures directed to the destruction of 

 mosquitoes and the protection of the sick against the 

 bites of these insects. 



11. While the mode of propagation of yellow fever has 



