]34 MODE OF TRANSMISSION OF YELLOW FEVER 



prejudice against excavations and dredgings during 

 certain seasons, notably in the summer montlis, and 

 works of this nature, in spite of tlieir importance 

 and urgency in preserving the health of the com- 

 munity, are deferred for an old tradition, and that, 

 too, after Havana and the Isthmian Canal Zone 

 have proved the absurdity of it. It demonstrates, 

 however, that the newer facts are not yet fully accepted 

 by a section of the public, and that those measures 

 against yellow fe\'er which have now been proved to 

 be the only ones of avail, are not fully adopted. It is 

 hardly necessary to add that in consequence valuable 

 time is lost, and lives and commerce sacrificed. 



When it is remembered that the Sfc^ofNijia calopus 

 is present throughout the year, and that in consequence 

 a town in the tropics in the yellow fever zone may 

 be as liable to infection in the autunm as in the 

 summer, or in the spring, it is obvious that if the 

 exca\'ated or dredged material contained some poison 

 which inoculated the stegomyia or infected man, it 

 would be as effective in the autinnn as in the summer 

 or spring, and dredging or exca\'ations would be 

 equally harmful at any time of the year ; it would 

 be impossible to say, as has been said, when " digging 

 operations might be safely commenced." But there 

 is no scientific evidence whatever, as we have seen, 

 to show that dredged or excavated material is infective, 

 and the prejudice does not appear to me to l)e shared 

 by the natives. Dredging operations have been blamed 

 as the cause of the outbreak in Belize, but the fact 

 is lost sight of that at the same tijne the fever had 



