HABITS AND YELLOW FEVER CONTROL 267 
Accordingly, from the eighteenth to the twenty-eighth day the observer draws 
his conclusions from a single mosquito. 
It appears necessary to deal with this subject in detail, for it involves questions 
of methods of prophylaxis of yellow fever. Wrong deductions, based upon 
inconclusive experiments, not alone because of the few mosquitoes employed but 
also on account of the faultiness of the experiments themselves, can produce 
the most serious consequences. The absence of accuracy in indicating the exact 
time of biting, in the above experiments, is most regrettable and invalidates 
them. This becomes at once apparent from the following extracts: Experi- 
ment I. “2d day: bites (1 or 2 only) between 3 and 6 o’clock in the morning, 
in darkness.” “3d day: bites between 1 and 5 o’clock in the morning.” “ 6th 
day: bites between midnight and 5 o’clock in the morning.” “16th day: bites 
in the night, between 1 and 6 o’clock in the morning.” Experiment II. “ 6th 
day: bite in the morning between 1 and 6 o’clock, in darkness.” “12th day: 
bite at night between 2 and 5 o’clock in the morning, in darkness.” “18th day: 
bite between midnight and 6 o’clock in the morning.” “27th day: bite in the 
night, between midnight and 6 o’clock in the morning.” 
In the second experiment the mosquito bit twelve times, but, as the experi- 
menter wishes us to believe that Aédes calopus becomes nocturnal after the sixth 
to eighth day, we need consider only the bites from the sixth day on. In this 
time the mosquito fed ten times. Five of these bites are indefinitely placed 
between midnight and 5 or 6 o’clock in the morning; in other words the in- 
vestigator was asleep during those hours. In the summer, at Rio de Janeiro, it 
is already daylight at 5 o’clock, and from what we know of the habits of calopus 
we do not hesitate in asserting that these bites were inflicted at daybreak. This 
leaves five credibly nocturnal bites and four of these admittedly took place with 
artificial light. Viewed in this manner the experiments may be said to be in 
accordance with the general impression of the habits of calopus. 
Goeldi devotes a special chapter to this subject and hotly attacks the assertions 
of the French commission. “ How can the most illustrious doctors of the French 
medical commission of the Institute Pasteur in Paris wish to prove, through 
their faith in their full scientific responsibility, that these Stegomyias in Rio de 
Janeiro ‘ont pique pendant la nuit, when here in Para, we, conscious of the 
same full responsibility, in view of our positive assertions for years, must declare 
the nocturnal bite as an exception?” The idea that calopus should change its 
habits after the first blood meal Goeldi characterizes as an absurdity. All the 
responsible investigators who have worked with mosquitoes in recent years dis- 
agree with the point of view of the French investigators. 
We must insist on this point on account of the danger which the French 
doctrine carries with it. It may lead those entrusted with yellow-fever prophy- 
laxis to abandon the safe methods and place their whole reliance upon protection 
against nocturnal bites.* 
* The Public Health and Marine Hospital Service of the United States has published quar- 
antine regulations, for fruit vessels visiting ports at which yellow fever exists, which appear to 
reflect the dogma of the French commission, These regulations were first published as 
Circular No. 27, Bureau of P. H. and M. H. S. in 1907, but they have been recently newly 
promulgated (Public Health Report, Washington, May 6, 1910, vol. 25, no. 18, pp. 604-607) and 
given still wider publicity through the Journal of Tropical Medicine and Hygiene (August 15, 
