17, 6 Trelease: Salt Requirements of Wheat Plants : 595 
GENERAL CONCLUSIONS 
A mass of experimental data such as is furnished by the pres- 
ent study suggests a very large number of questions and inter- 
pretations pertaining to the numerous details of the results. But 
it is desirable that the first analysis of these results should refer 
to none but the more broadly general problems. Only these 
general relations have been included in this study and, of these, 
those pertaining to the appearance of the plants and the dry 
yields have received principal attention in this discussion. 
It appears that the growth of these wheat plants for twenty- 
four days was nearly the same, whether a nutrient solution con- 
taining (1) Tottigham’s four salts, (2) Shive’s three salts, or 
(3) the latter with potassium chloride was employed, provided 
the set of salt proportions giving the best growth was. selected 
in each case. These three types of solutions appear to have 
been equally efficient for promoting the growth of the plants. 
The four-salt solution with potassium chloride apparently offers 
no advantages or disadvantages, as compared with either of the 
mixtures previously studied systematically. It was found that 
the presence of potassium chloride exerted no marked influence, 
at least for the total concentration principally studied (1.60 at- 
mospheres), when the four salts were used in the proportions 
giving highest top yields; and the best four-salt solution with 
potassium chloride contains the other three salts in nearly the 
same relative proportions as those in which the same salts occur 
in Shive’s best three-salt solution of the same total concentration. 
No injurious or retarding effect was observed that could be 
definitely ascribed to high partial concentrations of potassium 
chloride, even when this salt made up 0.9 of the osmotic value 
of the solution; and no characteristic injury was seen that could 
with certainty be related to the chloride. Retardation of growth 
associated with high chloride content of the culture solution 
appeared to be due to the accompanying low concentrations of 
the other three salts rather than to high partial concentration 
of the chloride. It is possible that a rather pronounced chlorosis 
may have been related to a high chloride content of the solution, 
but the evidence is not definite upon this point. 
While it seemed to be impossible to obtain better growth of 
these plants in the four-salt solution containing potassium chlo- 
ride than in Shive’s best three-salt solution, there is some evi- 
dence, nevertheless, that poorly balanced proportions of Shive’s 
three salts may have been improved for the growth of the plants, 
