Nov., 192 1 ] LYON — ^COMPARATIVE STUDIES ON RESPIRATION 
the rate of production of CO2 after the plants had been in the solutions for 
one hour. 
The figure shows that while the molecular proportions 99.65 NaCl to 
0.35 of CaClo give normal respiration, a decrease occurs at other proportions 
except that of 98.62 to 1.38 of CaCU. This form of the antagonism curve 
of NaCl vs. CaCl2 is unique, as is evident on comparing it with others in 
this series as well as with those in which growth, length of life, etc., are 
used as criteria.^ In order to explain this peculiar effect additional experi- 
ments will be necessary, and further discussion is deferred until these can 
be carried out. 
Summary 
1. Solutions of NaCl cause an increase in respiration, which is followed 
by a decrease, while solutions of CaCU cause only a decrease. 
2. After a sufficient length of exposure both NaCl and CaCU depress 
the respiration. In a mixture containing 99.65 mols of NaCl to 0.35 of 
CaCl2 the rate remains normal, while a mixture of 98.62 mols of NaCl to 
1.38 of CaCl2 causes a great increase in respiration. 
3. The antagonism curve of NaCl vs. CaCl2 is unique in that it has two 
maxima. 
Laboratory of Plant Physiology, 
Harvard University 
8 Antagonism curves with two maxima have been reported for other combinations of 
salts, but they seem to be somewhat different in character. Cf. Osterhout, W. J. V. 
Bot. Gaz. 48: 98. 1909. Brooks, M. M. Jour. Gen. Physiol. 2: 5. 1919. Lipman, 
C. B. Bot. Gaz. 48: 105. 1909; Bot. Gaz. 49: 41. 1910. Loeb, J. Jour. Biol. Chem. 
28: 175. 1916. 
