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ScHUFFNER (W.) & SwELLENGREBEL (N. H.). De Anophelinen in 

 Deli in Verband met de Uitbreiding der Malaria. [Anophelines in 

 Deli in Connection with the Spread of Malaria.] — Meded. Burger- 

 lijken Geneesk. Dienst in Nederlandsch- Indie, Baiavia, 1917, 

 no. 4, pp. 1-24, 19 figs. [Received 20th March 1918.] 



In the jDast malaria was of so little importance in Deli (Sumatra) 

 that remedial measm-es were not considered necessary. Of late years, 

 however, the disease has been increasing. On the estates of the 

 Senembah Company, which cover about 231 square miles, blood 

 examinations have been regularly made during 15 years, and whereas 

 the number of cases remained at about 17 per mille up to 1906, they 

 then slowly rose to 25 per mille, afterwards rapidly increasing until 

 they reached 79 per mille in the first half of 1913. The unfavourable 

 character of these figures is emphasised by the fact that the chief 

 increase concerns the malignant type, which in 1913 was seven times 

 as great as in 1909. The quartan form has increased four times, 

 wiiereas the benign tertian form has not participated in the rise. 

 During 1907-1913 the quartan form was mostly found in the hilly 

 districts, whilst this was only the case with the malignant tertian form 

 in the later years. The cause of the increase of these two forms is 

 therefore not the same. Cases of quartan malaria increase after the 

 rainy season, while those of benign and mahgnant tertian increase 

 during it. In Deli the variations of temperature are too slight to 

 account for these differences. There is probably a relation between 

 the seasonal differences in the number of cases and the number of 

 Anophelines. In Deli the mosquito-carrier of benign and malignant 

 tertian malaria appears to develop best in autumn and winter, and that 

 of quartan malaria about three months later, and the transmitting 

 species are probably not the same. It is also possible, but not probable, 

 that a seasonal immunity of the Anophelines obtains in Deli. The 

 statistics recorded in connection with the Senembah Company refute 

 the view that the increase of malaria is due to the great immigration 

 of Javanese since 1909 as a result of rubber cultivation. It is therefore 

 necessary to assume that in former times conditions were unfavourable 

 to infection, or, in other words, that there was a lack of transmitting 

 Anophelines. Either present-day conditions are more favourable to 

 the indigenous mosquitos or new species have been introduced. The 

 knowledge of the Anophelines of Deli is insufficient to allow of this 

 point being decided. After insisting on a more detailed knowledge of 

 Anoj)helines, attention is drawn to the fact that no great difficulty 

 attends the determination of the species already known. 



A description is given of the following species : Anopheles (Cellia) 

 kochi, Don., A. (Myzomyia) rossi, Giles, A. ludlowi, Theo. {vagus, 

 Don.), A. (M.) leucosphynis, Don., A. (M.) punctulatus, Don., 

 A. (M.) albirostris, Theo., A. (Myzorhynchus) sinensis, Wied., 

 A. (M.) barbirostris, Wulp, and A. (M.) albotaeniatus, Theo. 



The notes given on the distribution of Anophehnes in Sumatra are 

 substantially the same as those in a paper a'ready abstracted [see this 

 Review, Ser. B, v, p. 26]. 



