WORK OF FRENCH COMMISSION 247 



"(12) The injection of defibrinated blood, kept in the laboratory under vase- 

 line oil for eight days at least, gives a relative immunity. 



"(13) The serum of convalescents is endowed with clearly preventive prop- 

 erties. 



"(14) The immunity given by the serum of a convalescent is still appreciable 

 at the end of 26 days. 



"(15) The serum of the convalescent appears to have therapeutic properties. 



"(16) As proved by Eeed, Carroll and Agramonte, yellow fever is produced 

 by the puncture of Stegomyia fasciata [ — Aedes calopus^. 



•*(17) To be able to produce the illness with man, this mosquito must be in- 

 fected, previously, by absorbing the blood of a yellow-fever patient during the 

 first three days of the sickness. 



"(18) The infected mosquito is dangerous only after an interval of at least 

 12 days after it has sucked virulent blood. 



"(19) The punctures of two infected mosquitoes may bring about a very 

 severe case. 



"(20) The mosquito appears to be more dangerous in proportion with the 

 length of time which has elapsed after infection. 



"(21) The puncture of infected mosquitoes does not invariably give yellow 

 fever. 



"(22) When the bite of infected mosquitoes is ineffective this does not give 

 immunity against a virulent injection. 



"(23) In the region of Eio de Janeiro, as in Cuba, no other mosquito than 

 * Stegomyia fasciata is connected with the transmission of yellow fever, 



"(24) Contact with a yellow-fever patient, with his belongings or his ex- 

 cretions is incapable of producing yellow fever. 



"(25) Aside from the bite of infected Stegomyias, the only known method 

 of conveying the malady is the injection, into the system of a susceptible subject, 

 of blood coming from a patient and taken during the first three days of the 

 malady. 



"(26) Yellow fever can assume a dangerous character only in regions in 

 which Stegomyia fasciata exists. 



"(27) The prophylaxis of yellow fever depends entirely upon the measures 

 taken to prevent Stegomyia fasciata from puncturing the sick man and the 

 healthy man. 



"(28) It is necessary to remember that the period of incubation of yellow 

 fever may be prolonged to thirteen days. 



"(29) Stegomyia fasciata is frequently parasitized by fungi, by yeasts and by 

 Sporozoa. None of the parasites so far found have any relation to yellow fever. 



"(30) We have not been able to find, either in the mosquito or in the blood, 

 the causative organism of yellow fever." 



Two years later Marchoux and Simond published a brief note in the Comptes 

 Eendus des Seances de la Societe de Biologic (1905), on a possible hereditary 

 transmission of the virus of yellow fever in the yellow-fever mosquito. This 

 note, which created a great sensation at the time, and which still suggests a very 

 important factor in the possibilities connected with Aedes calopus and with 

 yellow fever, is here given in full. Similar results have never since been ob- 

 tained, and the observation must be deemed inconclusive to a certain degree 

 until verified by a series of similar experiments with similar results. 



" Since 1903 our attention has been directed to the fact that, in certain por- 

 tions of an endemic zone, it is sometimes difiicult to find a case of recent date as 

 the origin of the new cases which appear at the time, No doubt existed that 



