26 
cause they had been examined previously in September, 1914, and, 
with few exceptions, had not changed their place of residence. It 
was found that none of the 103 persons had received specific treat¬ 
ment, so that the recoveries (so far as the microscopical findings can 
demonstrate) were spontaneous, and the continued presence of para¬ 
sites could be ascribed either to relapses or to latent infections. In 
this group 48 cases were found still to harbor the malaria organisms, 
while the remaining 55 were negative at the time of the reexamina¬ 
tion. The positive cases were distributed as follows: 
Thirty-three (68.7 per cent) subtertian, of which 14 harbored gametocytes. 
Fifteen (31.3 per cent) simple tertian, of which one harbored gametocytes. 
It is of interest to note that 8 of the 15 gametocyte carriers were 
also crescent carriers in September, 1914. 
These 15 infected persons, according to the medical records of the 
plantation health officer, showed no clinical symptoms of the disease 
during the winter period. 
The importance of the public health relation of gametocyte car¬ 
riers was brought vividly to the attention of the investigator in the 
discovery of three infected Anopheles quadrimaculatus in dwellings 
which were definitely proved to contain individuals harboring 
gametocytes. These persons are included amongst the eight infected 
with gametocytes in September, 1914, and again in March, 1915. 
The finding of these infected mosquitoes and the demonstration of 
the probable human sources of the infection serves to show for this 
region the intimate relations existing in the perpetuation of the dis¬ 
ease through the winter and in linking together the two malarial 
seasons—autumn and spring. 
SUMMARY AND CONCLUSIONS. 
The review of the literature on the overwintering of malaria 
organisms in man and mosquito and on the habits of anophelines 
during hibernation leads to the impression that the conditions found 
elsewhere are essentially reproduced in the region investigated in 
the southern part of the United States. 
Hibernation studies during Febuary-June, 1915, were made in 
territory comprising 15 plantations in Bolivar and Washington 
Counties, Miss., having a malaria index of over 40 per cent. 
Search for hibernating anophelines was conducted in places com¬ 
monly known or likely to harbor them. The places inspected in¬ 
cluded residences, outbuildings, animal sheds, cotton houses, swampy 
and dry woods. Mosquitoes were found to be generally absent from 
all places except under houses and in the depth of woods. Interiors 
of dry hollow trees and those with roots in standing water were 
devoid of resting anophelines. This was ascertained by the aid of 
electric torches and by sulphur fumigation. 
