37 
are ten species in the same zone. The more exposed the 
rocky shore, the more do the chasmophytes dominate. 
A good deal of the halophytes of the sandy beach are. 
found in the vegetation of the rocky shore as well. 
Of course, the genesis of the zones in the halophytic 
formation are essentially due to the upwards decreasing 
salt percentage. At this point the physiological re¬ 
searches must be taken into consideration. 
Part II. The osmotic pressure in the leaf cells 
(epid. and mesophyll) of most of the halophytes was 
determined. The results are put together in Tabel I 
(p. 2) and II (p. 7). The mesophyll had in general 
a greater pressure than the epidermis. 
a. The succulent Sedum maximum and Suaeda 
maritima have a low pressure (0,so mol. saccharose),- 
which is in accord with the results of Livingston, 
Fitting and Falck. 
The halophytic and somewhat succulent Cochlearia 
officinalis , Crambe maritima and Honckenya peploides have 
also a strikingly moderate pressure (0,33—0,4 7 mol. NaCl), 
which may be due to the fact, that these plants occur 
some way up the beach, where the salt percentage 
is low. . 
Spergularia salina (and Scirpus maritimus ) living 
in the litoral zone have a pressure in the mesophyll (0,so 
mol.), which exceeds the pressure of sea water (=r 0,38 
mol. = 2,176 % NaCl) with about 0,4o mol. 
The xerophilous Armeria elongata (0,so—0,63 mol.) 
has a relative high pressure. 
The highest pressure was found in Atriplex latifo¬ 
lium (0,95— >l,o mol. NaCl), which explains the presence 
of this plant in several zones, even down in the lito¬ 
ral one. 
b. The permeability of several halophytes for so¬ 
dium chloride and other salts was investigated using 
the method of Fitting (Tabell Y p. 22). The re- 
