DEP U. TREUBIA VOL. II, 2—4. 
1919 must have been intermediate between 1918 and 1917, probably a little 
nearer to the former year than to the latter. 
We can now proceed to a closer study of Table VIII. In it is clearly 
expressed the very large production of rossii in November and also still 
in December 1918. Also in January and February 1919 the rossii production 
is still fairly large; after this however it gradually declines as time goes 
on, reaching a minimum in August 1919. In September 1919 the ponds 
near Fluit exhibit once more a larger production of rossii, this being then 
evidently the first indication of the new great autumnal production of rossii. 
Table VIII shows clearly that the months of May-August 1919 
were distinguished by the smallest production of rossii. The Jludlowi 
production on the other hand was in the same months generally largest, 
as is likewise visible in Table VIII. In connection with this it only occurred 
in the months of April to September (1919), and, if we leave the ponds 
of Heemraad Oost and Heemraad out of consideration, only in May, 
June and July (1919) (cf. the figures concerning the ponds of Pekulitan, 
Antjol and Jaagpad in the Tables VIII and X !)) that the /zdlowi production 
was occasionally greater than the rossii production. On the other hand 
the greatest /udlowi production that we could observe occurred in exactly 
the same month as the greatest production of rossii, viz. in November 1918, 
and that in the ponds of Heemraad Oost in which, contrary to what 
had happened in most of the Batavia ponds in the latter half of 1918, the 
salinity had until that moment continued so low, that in the spot where 
the mosquito-nets were set, it only amounted to 13.1 °/o. 
There is not in my opinion any reason for surprise on finding that a 
dry autumn like that of 1918, apart from the question of the salinity, is 
favourable to both the rossi production and the /zdlowi production. 
For in no season of the year do so few mosquito-imagines fall victims 
to rain and wind and will consequently so many females be able 
to return to the breeding-places and lay their eggs there, as in a period 
when the East-monsoon no longer prevails forcefully and regularly and 
when very little rain comes down. 
Apart from this it is clear enough that the differences of the annual course 
of the /zdlowi and of the rossii production is almost entirely dominated by the 
fact that the /zlowi production is to a high degree dependent on the salinity 
whilst on the contrary the production of rossii is quite independent of this factor 
at least within the limits of the salinities observed. Only in consequence 
of the fact that the /zdlowi-production is highly dependent on the salinity, 
the maximum J/udlowi production is shifted to the middle of the year, 
and to be precise, in accordance with the influences discussed above 
(pages 276-278) to the latter part of the first half and the very beginning of 
the second half of the year. In places where the influence of the salinity 
1) As remarked before Table X is related to Table VIII, as Table IX to Table VII. 
For this compare the discussion of Table IX on page 272. 
