30 ANDREW BALFOUR. 



Amongst the more important of the earher investigations is that by de Vogel in 

 the Dutch East Indies. As Howard, Dyar and Knab point out, he disproved certain 

 conchisions of the Itahan authors Perrone and Vivante, who stated that the maximum 

 proportion of sodium chloride in water which the larvae of Anophelines could resist 

 was under 2 per cent. Working chiefly with the larvae of A. rossi, Giles, de Vogel 

 found that a considerably higher percentage of sodium chloride, i.e., as much as 2-88, 

 was not detrimental. His summary was as follows : — 



"1. There are species of Anopheles which can live very well in sea-water. 



" 2. These mosquitos lay eggs which develop even in sea- water which has been 

 evaporated to half its original quantity. 



" 3. These larvae in the gradually evaporating pools of sea- water can stand an 

 evaporation of the water to one-third of its bulk, but do not appear to 

 transform to adults if the concentration be greater than this. 



"4. The larvae coming from eggs laid in sea- water of high concentration can 

 accomplish their entire metamorphoses in almost the normal time. This 

 is true even when the water has such concentration that the development 

 of larvae originally hatching in unconcentrated sea-water would be retarded 

 by this salt water." 



Later work by Carruthers and Christophers in the Andamans and also by Banks 

 in the Philippines and Swellengrebel in Java, suggests that de Vogel was probably 

 dealing with A. ludloit'i, Theobald, rather than with A. rossi, the two mosquitos 

 being very similar. 



A comparatively early record is that by Foley and Yvernault, who, in 1907, found 

 Pyretophorus chaitdoyei, Theobald, breeding in Algerian waters of which the salinity 

 was greater than that of sea-water. P. chaudoyei is now called A. multicolor, an 

 x\nopheline which comes very near A . hispaniola, Theobald, which, again, is probably 

 identical with the well-known Egyptian species A. turkhudi, Liston. As regards the 

 last-named, Gough has recorded the occurrence of its larvae in a brook of highly saline 

 water at Helouan, and succeeded in rearing them from water containing 2 per cent, of 

 salt. On the other hand Willcocks {loc. cit.) found that a 1 per cent, salt solution 

 proved fatal to the larvae of A . {Cellia) pharoensis, Theobald, a common Anopheline 

 of Egypt. 



Banks in 1908 showed that in the Philippines A. hidlowi, Theobald, a mosquito 

 mentioned by Dr. Dalziel in relation to the Andamans, breeds in both salt and fresh 

 water, and that in certain places they were present in water strongly impregnated 

 with lime and also containing much aluminium sulphate. 



Clerc in France found the larvae of a Culicine, Ochlerotatus, {CiUicada) cantans, 

 Meigen, in sea-water containing 44 grammes of chloride of sodium to the litre, and 

 recorded his observations in 1909. He noted that these larvae survive when trans- 

 ferred to fresh water, whereas, on the other hand, if the young larvae of A . maculi- 

 pennis are placed in salt water they die. The older larvae, however, survive and 

 become pupae and imagines. 



In 1910 Gholap at Bombay discovered the larvae of A. stephensi, Rothwell, in 

 sea-water. The ponds in which they were found contained vegetable growths. 



North American work on the subject, so far as Anophelines are concerned, includes 

 the observations of Chapin, who in Rhode Island found Anopheles larvae flourishing 

 in brackish coastal waters, and those of Smith on the larvae of A. quadrimaciilatus, 

 Say, in the saline waters of New Jersey, and the records demonstrating the breeding 

 of A. crucians, Wiedemann, in similar localities both in New Jersey and Louisiana. 



Stegomyia fasciata, Fabricius, figures in the list of mosquitos given by Dr. Dalziel 

 as breeding in boats and canoes, the water in which was for the most part brackish. 



