24 
Table No. VI . — Summary of results of blood examinations, February-March, 
1915. 
Total persons examined_1,184 
Positive for malaria_ ; _ 492 
Malaria index_per cent_41. 55 
Omitting mixed cases and one quartan: 
Subtertian (317 cases)_i___do_ 64.4 
Tertian (166 cases)-do_ 35.6 
Number of gametocyte carriers_ 122 
Subtertian cases with gametocytes_ 104 
Tertian cases with gametocytes- 18 
Percentage of malarial cases with gametocytes_per cent_24. 8 
Cases of quartan- 1 
Cases of mixed infections (excluded in the tertian and subtertian totals)- 8 
Classification of microscopical findings. 
Scanty +, 1 organism per 40 fields and over_ 258 
Few ++,1 organism per 25 fields_ 198 
Moderate + ++, 3-5 organisms per field_ 34 
Numerous + + ++, 6-10 organisms per field_ 1 
It will be seen from the summary of results of blood examinations 
that a sufficient number, nearly one-fourth, of the persons found in¬ 
fected harbored the sexual parasites. Material was thus provided for 
mosquitoes to carry on the spring cycle of new infections. This state 
of affairs was no doubt continued uninterruptedly, as it was observed 
that relatively few of the human carriers were aware of, or were 
concerned about, their infections. 
An insidious condition favoring mosquito transmission thus ex¬ 
isted here, as little or no efficient protection against mosquito trans¬ 
mission was provided. Of the total number of infections, namely, 
492 persons, only 35 persons were known to develop active symptoms 
subsequent to taking this index. In addition to these, 14 cases of 
clinical malaria were reported, but not included in the total infected, 
as they were not examined by the writer. 
The latent character of the infection may be appreciated in the 
prolonged search for the parasites in many of the blood smears ex¬ 
amined. In 456 thick-blood films organisms were scanty or few, and 
in 258 thick films they were exceedingly scanty, and if corresponding 
thin films had been examined would doubtless have been found nega¬ 
tive. 
The parasitological conditions present shortly preceding the time 
when the mosquitoes sought places for hibernation can best be shown 
in a malaria index of the persons living in this region during the 
fall of 1914. The table following shows the results of examinations 
of 1,666 persons residing in the various plantations in which hiber¬ 
nation studies were conducted. The malaria survey which it rep- 
