44 BOTANICAL GAZETTE [JANUARY 
The last-named investigators found in their experiments with the 
white lupine (Lupinus albus) and with alfalfa (Medicago sativa) 
that when CaCl, was added to MgSO, in about equal proportions 
the plants exhibited about 160 times the tolerance for the latter salt 
a that they did in solutions of MgSO, alone. They 
found further that the antagonism between CaCl, and 
Gk MgCl,, though not so great (increasing the tolerance 
about 40 times), was nevertheless very marked, and 
4 — ae - 
Sean ei NE ed eee ge a 
ee 5 es Saae 
ose = 
2 
mg| MgCl Calle 
rae | | | we 
APC FE E F G H  f28 
Fic. 1.—The ordinate at A represents the amount of ammonia nitrogen in milli- 
CaCl, solution of the same strength and with the same peptone content. The ordi- 
nates at the intermediate points represent the amounts of ammonia nitrogen formed 
in various combinations of the two salts as indicated in tables I and II. The full 
line represents results in table I; the broken line represents results in table II. 
where CaSO, replaced CaCl, the antagonism was very much greater 
between Ca and Mg than in either of the cases above cited. 
BENECKE? likewise found antagonism between magnesium and 
calcium in his work with Spirogyra. 
An antagonism between CaCl, and MgCl,, though slight, wa5 _ 
found to be none the less definite by Lors'® in experiments whic 
showed that sea urchin blastulae and gastrulae would swim about 
a mixture of the salts above mentioned for 48 hours, while each salt 
by itself would immediately prove poisonous at the concentration 
employed in the combination. Another interesting case in point 
may be noted in the experiments of the same investigator on Polyor 
chis,'™ a jellyfish of San Francisco Bay. Ina solution of so°° NaCl+ 
6°° MgCl,+1°¢ CaCl,, the rhythmical contractions of the margin g° 
9 Ber. Deutsch. Bot. Gesells. 25:322. 1907. 
° Amer. Jour. Physiol. 3:327. 1900. 
1 Jour. Biol. Chem. 13427. 1906. 
