﻿IX, B, 2 Sanitary Survey in Mindoro 167 



places of Myzomyia rossii and the prevalence of malaria confirms 

 the experiences which I have had at Olongapo,* Cervantes, Bon- 

 toc, Subig, Iloilo, Cavite, and Baguio. While other species of 

 anopheline mosquitoes occur in these localities in very limited 

 numbers, M. rossii is extremely abundant in all of them. It is 

 the species known to breed in both fresh and salt water,^ and 

 it is the only species in abundance in the Philippine Islands, 

 which is a proved carrier of malaria here as well as elsewhere.* 



6. THE DISEASE INDEX. (A) LABORATORY EXAMINATIONS 



By Ernest Linwood Walker, Ariston M. Guzman, 

 and ISABELO Concepcion 



In consideration of the part played by malaria in the mor- 

 bidity at the San Jose Estate, it was thought advisable to devote 

 chief attention in the laboratory during this investigation to the 

 examination of blood with special reference to malarial parasites. 

 The examination of faeces to determine the incidence of infection 

 with intestinal parasites was also undertaken, but owing to the 

 limited time at our disposal this series of examinations was 

 small. 



Blood smears were made from 1,095 out of the total population 

 of about 3,200 persons at San Jose. One large smear on a 

 1- by 3-inch microscopical slide was made from each person. 

 Time permitted the thorough examination of only a few of 

 these smears in Mindoro, and the remainder were brought to 

 Manila for examination. 



The blood smears were fixed in methyl alcohol, stained with 

 Giemsa's stain, and examined with a 1/12-inch oil-immersion 

 objective. With the aid of a mechanical stage, the preparations 

 were subjected to a very thorough examination for malarial 

 parasites. Attention Vv-as directed also in these examinations 

 to the presence of other blood parasites, such as spirochsetes, 

 Leishmania, and filarial larvae, and to any abnormalities in 

 the blood cells, such as leucocytes containing malarial pigment 

 and changes in the red blood corpuscles resulting from anaemia. 

 Time did not permit making red and white blood-corpuscle 

 counts, but the haemoglobin was estimated in most of the cases by 

 the Tallquist scale, and differential leucocji« counts were made 

 of a certain proportion of the blood smears which showed 

 malarial parasites. In these counts, owing to their large num- 



* This Journal, Sec. B (1907), 2, 513 et seq. 

 'Ibid. (1908), 3, 335 et seq. 



'Theobald, Monograph of the Culicidae. London (1907), 4, 47; (1910), 

 5, 19 (bibliographical). 



