EFFECTS OF ACID AND ALKALINE SOLUTIONS UPON PLANTS 42 1 
of cotton and transferred to sterilized glass bottles of 250 c.c. capacity. 
Each solution contained one plant and each experiment was con- 
tinued for 15 to 20 days under greenhouse conditions. A record was 
made every five days of the weight of water absorbed, the quantity 
transpired, and the gain or loss in the weight of plants. The curves 
of figures I to 4 are based upon the data contained in tables IX to X, 
and indicate graphically the course of the water relation. It may be 
remarked, incidentally, that the physiological reactions of the plants 
proceed at an unequal pace in the various solutions, even though the 
external conditions which affect the rate are kept alike. The note- 
worthy points are that the progress, as represented graphically, attains 
in almost all cases a maximum on the fifth day; thence the rate falls 
off rapidly, — with a recoil and nearly proportional lowering on the 
tenth day; after the adjustment has occurred there is a gradual 
increase in responsiveness to the solution which becomes more char- 
acteristic on the fifteenth day. A moment's study of the data or of a 
few of the curves will show how hazardous are conclusions concerning 
the stimulating or inhibiting effect of a solution when based upon 
results made at arbitrary intervals of time or under unlike conditions. 
Another point of interest is the fact that during the first five days, 
stimulation and the rate of the reaction is much more rapidly effected 
by acid than by the same concentration of alkali (tables VII and VIII). 
A very striking contrast is obtained also by observing that an increase 
in size of the root system is not necessarily connected with an acceler- 
ating action upon absorption or transpiration (tables IX to XII). 
The chief results of the experiments may be described as follows: 
1. During a period of fifteen days, tomato cuttings absorb and 
transpire less water in an acid solution of the concentration here 
employed than in distilled water (table VII). An exception is H2SO4 
w/3200. The plants absorb more water in a HNO3 n/Soo than in an 
equinormal HCl solution, and less in sulfuric and acetic acids in the 
order named. There is a great difference in the relationship between 
the quantity absorbed and transpired and the concentration of the 
acid. A point is reached in the solution of HCl and H2SO4 beyond 
which a further increase or decrease in concentration is followed by a 
diminished absorption and loss of water, while in solutions of HNO3 
and CH3COOH the absorption and transpiration of water varies 
inversely as the concentration. 
2. At the concentrations employed the absorption and transpira- 
