270 TREUBIA VOL. Il, 2-4 
As stated before (page 261) one can easily convince oneself at the Batavia 
empangs of the fact that at least the dense compact conglomerates of water 
plants, consisting in the first place of Chaetomorpha, which are to be 
seen in our photos 2, 3, 4, 6,-8, 9, 14 and 15 (Plates VII, VIII, IX, XI, XIV, 
XV, XXII and XXIII) mechanically and very greatly protect the Anopheline 
larvae against Haplochilus panchax (HAM BUCH.). 
| have already mentioned in a few passages that the larvae and pupae 
of the dangerous malaria-transmitter Myzomyia ludlowi THEOBALD, and 
of Myzomyia rossii GILES, which if perhaps not quite innocuous, is at 
least far and far less dangerous, are found in immense numbers in the 
Batavia empangs. Compared with those myriads the numbers of a few 
other species of Anophelines also sometimes produced by the Batavia 
empangs are a vanishing quantity (cf. VAN BREEMEN (#), (29) ). 
Now in the first place the investigation carried out by Mr, VAN BREEMEN - 
and myself disclosed the fact that there is a great difference between 
Myzomyia ludlowi THEOBALD and Myzomyia rossii GILES in the way they 
react upon the great increase in the salinity of the pond-water such as may 
take place in the course of a dry East-monsoon (cf. Chapter II). 
We made this discovery in October 1918. The empangs of the western 
extremity of the Batavian zone of marine fish-ponds from Muara Karang 
to Pekulitan inclusive, as a matter of fact produced no more Myzomyia 
Indlowi THEOBALD after June or July 1918, but continued to produce still 
large quantities of Myzomyia rossii GILES. The ponds of Heemraad Oost 
and Heemraad on the contrary continued also in the second half of 1918 
to produce besides Myzomyia rossii GILES also and continually large 
numbers of Myzomyia ludlowi THEOBALD (cf. VAN BREEMEN (°°), Table VI). 
On visiting those ponds of Heemraad and Heemraad Oost on October 
22nd 1918, we found that whilst the ponds of the western extremity of 
this part of the Batavia empang-belt were altogether dry, the empangs 
situated nearer the mouth of the Gunung Sahari Canal contained the 
normal quantity of water, in which were growing besides Enteromorpha 
and plenty of “tay-ayer” (cf. Chapter IV) also a very great quantity of 
Najas falciculata R. BR. We had learned before that with the strong 
increase of the salinity in the empangs in the western half of the Batavia 
empang-region (near Muara Karang, Fluit etc.) since the end of June 1918, 
Najas falciculata R. BR. had disappeared from those ponds (cf. Chapter IV). 
Hence we were not surprised to find on October 22nd 1918 that the 
water of the ponds of Heemraad Oost which were still producing many 
Myzomyia ludlowi THEOBALD, had a far lower salinity than most of the 
other Batavia empangs at the same time. 
The salinity of three samples of water collected that day from those 
ponds near Heemraad Oost, containing Najas falciculata R. BR, was 
11.5, 13.5 and 15.4°/,,. These low salinities were connected with the 
