SUNIER: Marine fish-ponds of Batavia. 281 
heavier rainfall than the average for many years. Accordingly in the autumn 
of 1917 the pond-water did not grow nearly so salt as in the autumn of 1918, 
in connection with which /zdlowi were produced in the end of 1917 by 
various empangs which produced no more /zdlowi at all in the end of 1918, 
as becomes apparent on comparing Table III with Tabie VI. 
In Table Ill I have put together a few data which were collected 
towards the end of 1917 by Mr. VAN BREEMEN and Dr. B. C. P. JANSEN 
of the Medical Laboratory (Geneeskundig Laboratorium) at Weltevreden, and 
handed ‚over to me by Mr. VAN BREEMEN. In Chapter II I have already 
mentioned how I obtained the salinity-figures of Table III by reducing the 
figures determined by Dr. JANSEN for the “amount of NaCl’. The 
Anophelines emerged from the larvae and pupae collected at the same 
time in breeding-places situated near one another in the same pond- 
system, were put together i.e. they were not kept apart for each breeding 
place. Hence in Table III are recorded each time for several salinities 
together the aggregate number of /udlowi and rossii females emerged. 
In the following examples selected from Tables III and VI the difference 
here being discussed between the /zdiowi-production in 1917 and in 1918. 
becomes clearly apparent: 
Salinity : Emerged from larvae 
Ponds ne. end” purge collected 
es lowest | highest) average Indlowi rossü Indtowi gg an 
EO EP TRE Le | QP [100 rossiggt): 
Muara Karang | 22 x117 12.0 0/50 30.5 oo 24.1 7 4 50 | 8 
ts 15/,. XL’ 18} 42.2 9/00 62.6 loo) 53.6 P/oo) 0 625 0 
Fluit 20 X[’17/14.0 9/99) 27.0 9/99/21. 75°/oo} 19 22 86 
3 5/,, X11’18|44.6 9/60 84.6 9/00 58.1 Ooo) 1 (at | 507 0.2 
44 60/60) 
Pekulitan 19 X1’17|19,5 2/60 24.0 2/00 21.5 foo} 11 31 35 
\ 26/9 X1’18/36.2 9/50 40.0 2/50) 38.8 °/oo} O 527 0 
In Chapter II we saw (cf. also Table I) that just as in 1918, high 
salinities, ranging between over 40 °/ and 74.5 °/oo, also appeared in October 
and November 1919, at least in Mr. Görs’s ponds near Muara Karang. In 
fry-ponds, which were however not in use at the moment, the salinity 
even rose as high as 93.2 °/o) on the 4th of November 1919. 
From the rain figures given above it is clear enough that in respect of 
the influence of the East-monsoon on the /zdlowi production in the empangs, 
1) It will probably be superfluous to remark that it is not the absolute magnitude 
of the mosquito-figures that is in question here, but the proportion between the numbers 
of ludlowi and rossii females emerged. | 
