718 INFECTION AND IMMUNITY. 



vention of Yellow Fever," Medical Record, Oct. 

 26, 1901; Parker, Beyer and Pothier, "Report 

 of Working Party No. 1" Yellow Fever Institute 

 Bulletin No. 13, 1903, Washington. 



importation Yellow fever cases and stegomyia work together 

 in the extension of the disease just as malarial 

 cases and anopheles do in the extension of ma- 

 laria; for the principles involved the chapter on 

 malaria may be consulted. Of particular interest 

 is the importation of the disease by means of ships, 

 since the invasion of the United States usually 

 comes about in this way. It is frequently stated 

 that ships lying one-half mile from shore are safe 

 from yellow fever; Grubbs, however, believes that 

 stegomyia may reach vessels lying within fifteen 

 miles of the shore if the wind is favorable. The 

 insect readily boards a vessel lying in an infected 

 port and may remain there at least during a sev- 

 enteen days' voyage. It may also breed in suitable 

 barrels or tanks of water on the ship. Under these 

 conditions it is readily understood how a ship, 

 leaving a harbor with a healthy crew, may be at- 

 tacked by yellow fever a few days after leaving 

 port; and how any quarantine measure at a new 

 port which does not involve the destruction of the 

 mosquitoes on the boat and the protection of the 

 patients from the bites of mosquitoes is inadequate. 

 ^ s s ^ a ^ e( ^? the nature of the virus is unknown. 

 Its filter ability was mentioned. A temperature 

 of 55 C. for ten minutes renders innocuous 

 the defibrinated blood of the infected ; according to 

 the French Commission (Marchoux, Salimbeni 

 and Simond) the virus is destroyed in five minutes 

 at this temperature. The latter also found that 

 defibrinated blood when sealed under vaselin re- 

 tained its virulence for five, but not for eight days. 



