97 



SWELLENGREBEL (N. H.), SCHUFFNER (W.) & SwELLENGREBEL DE 



Graaf (J. M. H.)- The Susceptibility of Anophelines to Malarial 

 Infections in the Dutch East Indies. — Meded. BurgerlijL GeneesL 

 Dienst. Nederl.-Indi'e, Batavia, 1919, no. 3, pp. 1-64. 



The practical value of the specific distinction of Anophelines is 

 based on the correctness of three premises : — The constancy of the 

 species, the limitation of the power to transmit malaria to some 

 species only, and the necessity for diflterent breeding-grounds in the 

 various species. The second of these points is mainly dealt with here, 

 the results of several series of experiments being showii in tabular 

 form. Other Dutch East Indian mosquitos may be as important 

 carriers of malaria as Anopheles ludlowi, but the latter undoubtedly 

 is a most dangerous one, the number of positive results with it in the 

 infectability experiments being the highest obtained for any. Two 

 specimens of A. ludlowi that had infected man on the 13th day were 

 dissected 72 hours later and a number of subtertian sporozoites were 

 found in the salivary glands. As they had taken blood twice a day 

 during five days, they probably carried cysts of different ages ; but 

 even were this not the case, the protracted production of sporozoites 

 may be explained by the unequal development of cysts of the same 

 age, sporozoites of varying sizes having been found in a specimen of 

 A. ludlowi that had fed only once on a carrier. Experiments with 

 malignant tertian parasites were more successful than with those of 

 benign tertian, perhaps because the latter are not so perfectly adapted 

 to development in A. ludlowi, or because the blood does not contain so 

 many gametes. Usually there is no reason to doubt the possibility 

 of further development of malarial parasites in the mosquito, if once 

 the oocyst stage has been reached, but in one experiment with^. sinensis 

 the malignant parasite was unable to mature. It was not possible 

 to determine whether the growth of the cysts was only inhibited or 

 whether they were continuously produced afresh and died after 

 reaching the stage of small cysts. One specimen of A. sinensis that 

 had infected man on the lOth day showed sporozoites in the salivary 

 glands 48 hours later ; the same explanation is advanced as for 

 A. ludlowi. Negative results were obtained with malignant tertian 

 malaria regarding the infectability of A. umbrosus. This disagrees 

 with Barber's findings in Malaya [see this Review, Ser, B, vi, p. 125], 

 but tallies with Roper's observations in British North Borneo [see 

 this Review, Ser. B, iii, p. 11]. The type of A, umbrosus with which 

 the present experiments were performed breeds in salt water near 

 the sea-coast and differs from the inland form in the presence in the 

 larvae of pilose internal clypeal hairs. It is possible that Barber's 

 results were obtained w^ith the inland form, which also sometimes 

 occurs in salt water. Negative results were also obtained with 

 A. umbrosus and tertian malaria. The positive results obtained in 

 A. barbirostris and A. koclii (with benign tertian) and A. punctulatus 

 (with malignant tertian) are remarkable, but the figure expressing 

 the percentage of infectability has little value owing to the small 

 numbers examined. The conclusion reached is that these three 

 mosquitos are not such good carriers as A. ludlowi. The experiments 

 with quartan parasites were remarkable because of the small percentage 

 of infected A. ludlowi, which is hardly larger than that of A. sinensis. 



