130 BOTANICAL GAZETTE [Avcust 
formula‘ as follows: 1ooo°* NaCl, 3m/8; 78°° MgCl,, 3m/8; 38° 
MgsSO,, 3m/8; 22°° KCl, 3m/8; 10°° CaCl,, 3m/8.° . 
This closely approximates the bay water. The plants thrive 
almost as well in it as in sea water, especially when a very little | 
NaHCO, or KHCO, is added to produce a neutral or faintly alka- 
line reaction. 
A series of solutions was tried, beginning with pure NaCl 3m/8 
and adding to it in turn MgCl,, KCl, and CaCl,, either singly or in 
combination, in the proportions given above. These salts were also — 
used in pure solutions of the same concentration at which they exist 
in the artificial sea water described above. : 
It should be said that little difficulty was experienced in deter- — 
mining the death point with sufficient precision. The color reactions 4 
and the microscopic appearance of the cells allowed this to be done : 
with sufficient accuracy, so that the results were not in doubt on this 
account. , 
The results of the experiments are set forth in the tables. The 
figures represent the average of four parallel series carried on simul- 
taneously. A control series was also carried on in which each solu- 
tion was made faintly alkaline by the addition of NaHCO,, KHCO,, 
or Ca(OH),. This had a beneficial effect during the first ime or 
three days of the experiment, but the final results were practically 
the same as in the other series. 
From a consideration of the results for Group 1 we may draw 
the following conclusions. 
1. The plants die much sooner in a pure sodium chlorid solutio 
(isotonic with sea water) than in distilled water. The poisonous 
effect of the NaCl largely disappears if we add a little CaCl, (10° 
CaCl, 3m/8 to tooo®* NaCl 3m/8); in this mixture the plants jive 
nearly as long is in distilled water. Addition of KCI to this m&® 
ture enables them to live longer than in distilled water. F urther 
addition of MgCl, and MgSO, enables them to live practically * 
long as in sea water. 4 
4 Van’t Horr, J. H., Physical chemistry in the service of the sciences I10f- Univ. ja | 
of Chicago Press, 1903. 
s This corresponds approximately to the proportion of Ca in the sea wate? of 
the bay. 
