278 TREUBIA VOL. II, 2—4. 
vegetation developed later and generally speaking a little less luxuriantly 
than in the spring of 1918. 
From the above it seems to me sufficiently proved that we have no 
right to conclude from the figures of Table VIIA relating to Pekulitan 
and Pegantungan, that the optimum for the /zdlowi-production is situated 
at salinities from 10 to 19.9°/,,. On the contrary everything points to the 
conclusion that in proportion as the salinity is lower the conditions, ceteris 
paribus, are also more favourable to the production of /zdlowi. Hence 
also the ponds of Heemraad and Heemraad Oost which contain water 
of a comparatively low salinity all the year round and in which I accordingly 
found even in August and September salinities below 10°/,,, ponds conse- 
quently to which a great part of the argumentation just offered does not 
apply, exhibited the greatest production of /udlowi at the lowest salinities 
(cf. Table VIIA). This explains at the same time why in Table XI the 
greatest production of /udlowi for the averages placed after A is found 
at salinities from 10 to 19.9°/,,, but for the average placed after a at 
salinities from O to 9.9°/,,. For from Table VII A which shows once 
more how the two series of general averages, concerning the whole empang 
zone were calculated, it is certainly apparent, that in the averages after A 
in Table XI the great /zdlowi captures of Heemraad and Heemraad Oost, 
in connection with the many times that in these ponds nets were set on 
one side over water of salinities from 0 to 9.9°/,, and on the other side 
over water of salinities from 10 to 19.9°/,,, are expressed insufficiently for 
the salinities from 0 to 9.9%, but too highly for the salinities from 
10 to 19.9 Joo. 
The regular, though small, increase of the /zdlowi-production in the 
ponds near Jaagpad in proportion as the salinities between 3.4 and 29.9 °/o9 
were higher and the fact that the ponds near Fluit exhibited an increased 
ludlowi-production at salinities from 30 to 39.9 °/, compared with the 
production at salinities from 0 to 9.9 and from 10 to 19.9 0), (cf. Tables V 
and VII A), must be accounted for likewise by the fact that during the 
prevalence of the higher salinities a number of circumstances were generally 
more favourable to the /zdlowi-production, which for that matter was never 
great in these cases, than during the prevalence of the lower salinities. 
The averages printed after B and b in Table XI relating to the rossii- 
production serve for comparison with the corresponding figures concerning 
the /udlowi-production mentioned after A and a. 
The production of rossii, fairly constant at salinities below 25 °/oo, 
suddenly increases rather importantly at salinities between 25 and 29.9 °/op. 
This increase of the rossii-production then continues fairly markedly as the 
salinities increase up to 69.9 0/4. I have already, though in somewhat dif- 
ferent words, pointed out how this phenomenon must doubtless be 
connected with the fact that when we made our observations the many 
other conditions apart from salinity which influence the size of the 
