402 



Climateric conditions of yellow 

 fever: 



Temperatures at which yellow 

 fever epidemics decline and cease 

 at New-Orleans. (Dr. Barton's 

 Report, 1854, Introduction, p. 

 xiiii). 



Minimum: 15,6° C. 

 Mean: 18,7° C. 



Degree of cold which did not ex- 

 '■'' ' return of yellow fever on 

 the "Plymouth" (see "Hygiene" 

 Med. Reports Navy Department, 

 Washington, 1879, p. 689). 



Freezing point. 



Degree of cold which proves 

 effective for the permanent arrest 

 of Yellow fever, (Laroche, II. p. 

 295). 



Severe frosts. 



Artificial heat wich proved 

 effective in arresting yellow fever : 

 Case of the Regalia (see Laroche, 

 on yellow fever II. p. 440). 



up to which yellow 

 exceptionally been 



Altitudes 

 fever has 

 propagated : 



Madrid, 1878, 2,000 feet. 

 New Castle (Jamaica) 4,000 feet. 



Vital conditions of the Culex 

 mosquito: 



Temperatures at which the 

 Culex mosquito is benumbed by the 

 cold. (7 experiments). 



Minimum: 15° C. 



Mean: 18° 

 Maximum: 19° C. 



Degree of cold which the Culex 

 mosquito can endure without losing 

 the faculty of reviving when the 

 temperature is again raised: (4 

 experiments) : below 0° C. 



Degrees of cold at which the C. 

 mosquito can no longer revive. 



("One experiment") : — 4° C. 



Degrees of heat at which the C. 

 mosquito becomes impeded in its 

 movements. 



(4 experiments) : Maximum: 39° C. 



Minimum: 37° C. 



Mean: 38° C. 



Degrees of heat after which the 

 C. mosquito does not revive: 

 (4 experiments) :Maximum: 43° 

 Minimum: 39° 



Mean : 41° C. 



Artificial rarefaction which the 

 Culex mosquito can endure without 

 necessarily losing the faculty of 

 biting again: those corresponding 

 to 2,000. 3,000. 4,300 feet 

 (estimated). 



Artificial rarefaction which 

 seems to deprive it permanently of 

 the power of stinging : 5,000 to 

 6.000 ft. 



At that time it might have been objected that, until the germ of the 

 disease was discovered, it would be impossible to determine whether the 

 cessation of yellow fever epidemics when the thermometer falls to 15° C. 

 was due to the influence of that temperature upon the mosquito or to its 

 action upon the infectious germ itself. This question, seems however to 

 have been resolved incidentally through one of the last experiments 



