274 | TREUBIA VOL. II, 2—4. 
it was observed, all sorts of circumstances exerted a heightening influence 
on that production. It would therefore appear to me that from the data 
collected by Mr. VAN BREEMEN and myself the inference ought to be made, 
as I have already had occasion to remark, that, within the limits of the 
salinities observed (3.4—84.6°/,,), the size of the production of rossii is 
independent of the salinity. 
We ought not to be surprised to find that for the different parts of 
the Batavia empang region the figures expressing the average ludlowi 
production per 10 M? and per night do not always exactly in the same 
way follow the modifications of the salinity (cf. Table VII A). It stands 
to reason that the magnitude of the /zdlowi-production does not depend 
exclusively on the salinity, but is also dependent on a great many other 
conditions. Most of those other conditions will doubtless influence the 
magnitude of both the /zdlowi-production and the rossii-production 
equally. Hence the combined effect of those other conditions must 
in my opinion find expression in the figures of Table VII B, stating the 
average production of rossii per 10 M? and per night, which latter produc- 
tion, I venture to repeat, is not influenced, within the limits of the salinities 
observed, by the variations of the salinity. 
The preceding may if necessary be rendered still clearer by the fol- 
lowing example. Taking the case of Heemraad Oost and placing for the 
different salinity classes side by side the figures denoting the average 
numbers of /udlowi-temales and of rossii-females produced per 10 M2 and 
per night, we get the following: 
Salinity : ludlowi® © : rossii QQ: 
0— 9907, 76 19 
10 — 19.9 0/,, 71 30 
20 — 24.00}, 21 95 
25 20/00) 25 220 
30 — 39.9 °/,, 11'/, 157 
For /udlowi we see the numbers of females produced per 10 M? and 
per night decreasing regularly as the salinity rises. Only at salinities 
between 25 and 29.9°/,, not fewer, but rather more /udlowi? © were 
produced than at salinities between 20 and 24.9°/,,. But if we consider 
how many more rsossii2Q were produced at salinities between 25 and 
29.9°/), than at salinities between 20 and 24.9°/,,, 1 am inclined to 
assume that in the cases when the salinities between 25 and 29.9 °/,, were 
observed, the conditions for the production of both species of Anophelines 
were on the whole so much more favourable than in the cases when the 
salinities between 20 and 24.9°/,, were observed, that in spite of the 
influence of the salinity working in the opposite direction, the /zdlowi 
production at 25—29.9°/,, was yet somewhat greater than at salinities 
between 20 and 24.90). 
