128 BOTANICAL GAZETTE [AUGUST 
It is noteworthy that the Ca and K, which are added to inhibit — 
the toxic effect of NaCl, are themselves poisonous at the concentra- — 
tion at which they are here employed. F 
These antagonistic effects of Ca and K toward a pure NaCl solu- — 
tion were illustrated still more strikingly in experiments on the egg 4 
of Fundulus. The newly fertilized eggs of this fish develop equally 4 
well in sea water and in distilled water, but die in a pure m/2 NaCl 4 
solution without forming an embryo. If, however, a small but defi- 7 
nite amount of a salt with a bivalent kation, even of such poisonous — 
salts as BaCl,, ZnSO,, and Pb(CH,-COO),, is added, the eggs will 4 
produce embryos. From these and similar observations LoEB Was 
led to formulate his conception of the necessity of physiologically 4 
balanced salt solutions, in which are inhibited or counteracted the — 
toxic effects which each constituent would have if it alone were a 
present in the solution. a 
The blood, the sea water, and to a large extent RINGER’S solution, — 
are such physiologically balanced salt solutions. The observations 
of HERsst, as well as those of RINGER, are easily explained on this — 
basis. The fact that the elimination of any one constituent from — 
the sea water makes the solution unfit to sustain life does not prove 
that the eliminated substance is needed by the animal for any purpose — 
other than to counteract the poisonous action of some other constlt 
uent of the solution. = 
Botanists have not thus far made use of these conclusions, for the — 
obvious reason that facts similar to those mentioned above have ne 
been observed in plants. I have recently made a number of expel 
ments which show that there exist in plants phenomena similar to 
those observed by Lors on Fundulus and other marine animals. 
The species of marine plants chosen for investigation may be 
divided into two groups: - 
Group 1 comprises plants which can live a long time in distilled 
water. It includes the following: BLUE-GREEN ALGAE, Lyngby 
aestuarii; GREEN ALGAE, Enteromorpha Hopkirkii; FLOWERING 
PLANTS, Ruppia maritima. Gg 
Group 2 is composed of plants which quickly die in distilled 4 
water. It includes the following: GREEN ALGAE, Enteromorph@ 4 
intestinalis; BRowN ALGAE, Ectocarpus confervoides; RED ALGAEs 4 
