218 Chlorine and Plant Growth [416 
The investigations here considered in a preliminary way 
were planned to supplement our knowledge of this subject. 
They are as yet in early stages of progress, having been begun 
under the auspices of the Wisconsin Agricultural Experiment 
Station. It was purposed to measure the responses of various 
plants, in form and in the weight of plant material produced, 
to the application of certain chlorides, and to determine any 
specific results brought about by this application of chlorine, 
upon the chemical composition of the plants. Greenhouse 
cultures were grown in nutrient solutions, in pure sand and 
in Miami silt loam, and field cultures were grown in loam. It 
may be said of these greehouse cultures, which were partly 
carried out in the winter, that, while growth is retarded by the 
decreased light intensities of the winter months, the partial 
control of climatic and soil conditions in such greenhouse cul- 
tures assures more reliable comparative results than are usually 
derived from field plots, with their natural fluctuation of 
climatic conditions from season to season and of fertility from 
plot to plot. 
In the water-culture experiments, in the greenhouse, the 
plants were grown to maturity, in either Tottingham’s or 
Knop’s nutrient solution,t containing Ca(NO,;),, KNO,, 
MgSO, and KH,PO,, in proper proportions, with a trace of 
iron as FePO,. The former had a total osmotic concentration 
value of about 1.75 atmospheres (0.4 per cent. of salts by 
weight) and the total osmotic value of the latter was about 
0.9 atmospheres (0.2 per cent. of salts by weight). In some 
cases chlorine was introduced by replacing the MgSO, of the 
4-salt solution with a molecularly equivalent quantity of 
MgCl, , in other cases KNO, was replaced by KCl, and in 
still other cases NaCl was superimposed upon the salts usual- 
ly present. Replacement of MgSO, by MgCl, resulted in an 
increased length of roots, for pea, wheat and clover, amount- 
* Tottingham, W. E., “A quantitative chemical and physiological 
study of nutrient solutions for plant cultures.” Physiol. Res. {: 
247-288. 1914. 
