SUNIER: Marine fish-ponds of Batavia. 261 
“It is evident from the study of plants in relation to mosquito control 
“by means of fish that it is highly desirable to remove from the ponds 
“those plants having leaves just below the surface of the water and to treat 
“algae in such a way as to make them useless as protectors of mosqitoes. 
“The presence of these plants was by far the most important obstacle to 
“be overcome in securing mosquito control in the many ponds in the 
“extra-cantonment zone of Camp Hancock”. 
It can be easily observed in the Batavia empangs that the Anopheline 
larvae are largely protected from the Haplochilus panchax (HAM. BUCH.) 
that devour them, by the dense conglomerates of water-plants, consisting 
in the first place of Chaetomorpha (cf. Chapter IV), that are represented 
in our photos 2, 3, 4, 6, 8, 9, 14 and 15 (Plates VII, VIII, IX, XI, XIV, 
XV, XXII and XXIII). Haplochilus panchax does not penetrate into those 
thick algal') masses, at least not far. On the other hand these masses 
of algae '), as shown by our catches with mosquito-nets, may produce 
great quantities of Anophelines whose larvae can a.o. be found in the 
filmy layer of water covering the algal') masses and in small openings or 
depressions in the upper surface of these conglomerates of water-plants, 
in which places the larvae are practically speaking perfectly safe from the 
Haplochilus panchax. 
Accepting accordingly that in the Batavia empangs the Anopheline 
larvae and pupae are certainly well protected from the voracity of 
Haplochilus panchax (HAM. BUCH.) in those places where a more or 
less dense submerged vegetation, reaching the surface of the water, 
has developed, which is not the case in open water, I am perfectly willing 
to admit the possibility of the view that perhaps the conditions of life amid 
the submerged vegetation are yet in other respects more favourable to 
the Anopheline larvae (and pupae) than in open water. One might for 
instance think with SWELLENGREBEL (%) of the food of the Anopheline 
larvae. 
SWELLENGREBEL (52) does not express any views as to the nature of 
this food. The intestine contents of some larvae of Myzomyia rossit 
GILES and/or Myzomyia ludlowi THEOBALD | found to consist of various 
fine vegetable and animal detritus, among which e.g. very small fragments 
of Enteromorpha, and of minute Diatoms. 
The facts are therefore briefly as follows: In those places in the Batavia 
empangs where the frequently mentioned submerged vegetation floating at or 
reaching up to just beneath the surface of the water occurs and, to a lesser 
degree, also where the overhanging marginal vegetation projects partly into 
the water, the conditions of life for the larvae (and pupae) of Myzomyia rossi 
GILES and Myzomyia ludlowi THEOBALD are so favourable, principally 
because of the mechanical protection against Haplochilus panchax (HAM. 
BUCH.), as to render possible the production of myriads of these Anophelines, 
1) cf. note page 209, 
