YELLOW FEVER AND THE LEPTOSPIRA 



879 



species requires a temperature never going below 22 C. at night 

 and rising regularly above 25 C. during the day. The females only 

 are dangerous as sources of infection. The insect, like Anopheles, 

 has the peculiarity of feeding chiefly at night. 



FIG. 99. STEGOMYIA FASCIATA. (a) Female. (6) Male. (After Carroll.) 



Experiments done by Reed, Carroll, Agramonte, and Lazear, to 

 ascertain whether the power of infecting was hereditarily transmis- 

 sible from the mosquito to following generations, were negative. A 

 positive result, however, has been reported by Marchoux and 

 Simond. 9 This question must still await more extensive research. 



ETIOLOGY OF YELLOW FEVER 



Numerous researches have been aimed at the elucidation of the 

 problem of etiology and a large number of different microorganisms 

 for which etiological significance was claimed, have been isolated 

 from dejecta, vomitus and secretions of patients. A few of these 

 claims have only historical importance, but may be mentioned be- 

 cause of the wide interest they aroused among bacteriologists in the 

 past. 



9 Marchoux and Simond, Comptes rend, de la soc. de biol., 59, 1905. 



