9 
Shipley (1915), writing of the eggs of the A. quadrimaculatus, states: “ There 
is no evidence that they can survive throughout the winter period. Every¬ 
thing that we know indicates that the egg must pass the period within the 
mother’s body, • and that they only attain maturity in early spring, when the 
weather becomes warmer.” 
It will be noted that there is a marked unanimity of expression 
indicating the belief that the mosquito phase of the overwintering 
of malaria is a negligible factor. These opinions are, to be sure, 
based on epidemiological data and show a uniform absence of experi¬ 
mental proof. However logical these expressions appear to be, the 
fact remains that the problem can not be dismissed as settled until 
further experimental data are presented. 
OUTLINE OF WORK. 
At the outset of the present work it was necessary to secure data 
contributing toward the solution of the following: In what habitat 
in the region under observation did anopheline mosquitoes hibernate? 
When did this occur, and under what limitations? In what form 
(egg, larva, pupa, or adult) did anopheline mosquitoes pass the 
winter ? What were the effects of temperature on the activities of the 
hibernating mosquitoes? Lastly, did anopheline mosquitoes harbor 
any form of the malaria organism during the dormant stage? 
A persistent effort was made, during February to June, 1915, to 
collect as much data concerning these points as was possible. 
A district comprising 15 plantations of the Mississippi Delta 
Planting Co., in Bolivar and Washington Counties of northwestern 
Mississippi, was selected for the purpose of this study by Surg. R. H. 
von Ezdorf, in charge of malaria investigations of the Public Health 
Service until his death in September, 1916. 
In a general way the places inspected were those known to have 
harbored Anopheles mosquitoes during the season when malaria was 
prevalent. The plantations selected for domiciliary visits were the 
most heavily infected of the 15 plantations, the malaria index regis¬ 
tering, at one place at least, as high as 58 per cent in September, 
1914. The following record gives the details as to the character of 
the places visited and the opportunities for infestation presented. 
Routine inspections were conducted in this manner for a period of 
six weeks, beginning February 5, 1915. During the first two weeks 
the writer had the cooperation of Sanitary Engineer Le Prince, who 
was assigned to field studies. His notes are incorporated in the 
account appended. 
NOTES ON FIELD EXAMINATIONS. 
February 5, 1915 .—Examined interior of buildings and outhouses connected 
with Dr. M.’s residence. They included ice house and harness room, which were 
very dark and tight (wind proof), but accessible to mosquitoes. The former 
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