EFFECTS OF ACID AND ALKALINE SOLUTIONS UPON PLANTS 43 1 
kinds to an acid or an alkaline solution shows that the reactions are 
specific and unlike with each salt employed (pages 421, 423). The 
order of effectiveness in inhibiting or in producing an increase in the 
water relations of plants may be stated as follows : 
{a) In a solution of hydrochloric acid the salts of sodium counteract 
to a marked degree the injurious effects of the acid and are preferable 
to potassium salts. The nitrates of any of these three bases give 
uniformly better results than the sulfates or chlorides. 
Calcium has a greater accelerating action in an unbalanced acid 
solution if combined with a sulfate, while potassium proves most 
corrective if used as a chloride. The beneficial effects obtained may 
be due to an indirect reaction between the different substances in the 
medium through changes induced by the plant. The acid radicle 
(NO3) is usually absorbed more rapidly, leaving behind the base ion 
or alkaline radicle (Na) , which then may give rise to a direct reaction 
between the difTerent substances in the medium. 
{h) In an alkaline medium (KOH) calcium salts are more bene- 
ficial and should be furnished preferably in the form of a sulfate. 
Sodium salts are more capable of altering the water relation of plants 
as chlorides, and potassium salts give uniformly a greater increase as 
nitrates. The relative effects of the anions and kations may be 
accounted for in a manner as pointed out in (a). 
3. The remarkable increase in weight which has attended the use 
of non-electrolytes, especially glycocoll and sucrose, proves ready 
digestibility of these organic compounds, their relative value in the 
maintenance and repair of constituents destroyed during growth in 
acid and alkaline solutions, and further indicates that water retention 
during growth may be limited by any factor which prevents the 
construction of food constituents, i. e. the chemosynthesis of proteins 
and carbohydrates. If this interpretation is correct, it follows that 
artificial organic fertilizers may supplement advantageously the use 
of mineral salts. 
4. The injurious properties of acid solutions (and probably also of 
acid soils and subsoils) may not necessarily be due to their acid char- 
acter. In itself acidity is not always a disturbing factor to growth 
and transpiration of plants. The apparent inhibiting action may be 
the effect of the presence of some salt, perhaps in large measure the 
reaction of the solutions after the plants have been growing in them 
for some time, retarding the rate of hydrolysis of substances in the 
cells of plants. 
