192 TREUBIA VOL. II, 24. 
In this pond also the Najas falciculata disappeared altogether as the 
salinity increased, to reappear again when the salinity had fallen in 
February 1919. 
I am however also acquainted with cases of a Najas falciculata-veget- 
ation, which had suddenly sprung up, succumbing again in a short time, 
without any reasonable motive for believing, in connection with my other 
data, that this could have been brought about by the rather oem 
increase of the salinity during the life of the Najas-vegetation. 
Thus on March 15th 1918 I found a good deal of Najas falciculata in a 
pond near Heemraad, the salinity of the pond-water being 5.9°/,). On 
March 19th and April 3rd following this Najas-vegetation was still 
growing well at salinities of 11.8°/,, and 10.6°/, respectively; but on 
April 16th it began to languish and die, the salinity being then 13.7 °/). 
On May 14th, a salinity of 17.1 °/,, prevailing, there was nothing left of 
all this Najas-vegetation. | 
In addition to the above my diary furnishes the following data relative 
to the occurence in the Batavia empangs of Najas falciculata, at a definite 
time, place and salinity: 
15 Ill’18 pond near Heemraad; S= 3.4 Jo); Najas falciculata present. 
19 I11’18 pond near Muara Karang; S= _ 6.3 °/o9; Najas falciculata present. 
3 [V’18 pond near Muara Karang; S = 10.8 °/o9; Najas falciculata present. 
2 VII’18 pond near Tjilintjing ; S = 21.6 Joo; old Najas falciculata 
overgrown with Oscil- 
latoria. 
2 VII’18 pond near Tjilintjing ; S = 25.3 °/oo; fine, healthy Najas fal- 
ciculata. 
2 VII’18 pond near Tjilintjing ; S = 31.1 °/o0; old Najasfalciculata over- 
grown with Lyngbya. 
22 X’18 pond near Heemraad-Oost; S = 11.5 °/o9; much Najas falciculata. 
22 X’18 pond near Heemraad-Oost; S — 13.5 °/,; much Najas falciculata. 
22 X’18 pond near Heemraad-Oost; S = 15.4 °/o); much Najas falciculata. 
24 XI1’18 pond near Heemraad-Oost; S = 20.2 °/oo; very much Najas falci- 
culata. . 
2 VII’19 pond B of Map Il; S = 13.6 °/oo; Najas falciculata present. 
2 VII’19 pond C of Map II; S = 10.7 °/o0; Najas falciculata present. 
2 VII’19 pond G of Map II; S = 17.1 °/oo; Najas falciculata present. 
In the second place the observation table (Table IV) contains the fol- 
lowing data concerning the occurence of Najas falciculata R. BR. in the 
Batavia empangs, which data are here found arranged in the order of the 
salinities : 
4.8 °/oo Muara Karang 13 V 719 
4.8 °/0 Heemraad-Oost 11 VIII ’19 
