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1920 
fact that the lower one of these two highest total concentrations 
(series 21, 0.0192 gram-molecule per liter, or 1 atmosphere) was 
much less concentrated than Shive’s best solution for young wheat 
plants. Whatever may be the details in this connection, it is 
safe to say that Shive’s wheat grew excellently in solutions with 
osmotic values of 1.75 atmospheres, or even higher, while the 
rice of the present studies failed to develop even fairly well, 
with any set of salt proportions, if the osmotic value was greater 
than about 0.4 atmosphere. Turning to the other plants that 
have been studied in a systematic way by Shive (1917), by 
Shive and Martin,^® and by Shive (soybeans, 1918), it will be 
seen that buckwheat gave about twice as much in dry yields of 
tops with the best sets of salt proportions for a total concentra- 
tion of 1.75 atmospheres as it did with the best ones for a con- 
centration of 0.1 or 4 atmospheres; so that it is evident that 
rice does not require nearly so high a total concentration for its 
best growth while young as does buckwheat. Also, Shive ob- 
tained excellent growth for soy beans with a total concentration 
value of 2.5 atmospheres, which indicates that this plant thrives 
best for the first few weeks in solutions much more concentrated 
than can well be borne by young rice plants. It may safely be 
said that rice differs remarkably from wheat, buckwheat, and 
soy bean, in that, in the case of these three plants, the total con- 
centrations of the nutrient salt mixtures that show best growth 
in the young ones (when the salt proportions are properly ar- 
ranged) have osmotic values well above 1 atmosphere, while 
this value is only about 0.5 atmosphere, or even lower, in the 
case of rice. 
These considerations regarding the comparative ability of 
rice, wheat, buckwheat, and soy bean to withstand high total 
concentration of the culture solution, providing the salt propor- 
tions are properly arranged, will be still further emphasized 
when the quantitative data of the present studies are considered. 
Throughout these series with the 4-salt solution type A, the 
yellowing of the leaves was generally more intense for the 
smaller plants; that is, chlorosis and stunted growth appeared 
to be controlled by the same sets of conditions. The more pro- 
nounced differences in size were paralleled by similar differences 
in dry yield. 
““ Shive, John W., and Martin, William H., A comparative study of salt 
requirements for young and for mature buckwheat plants in solution cul- 
tures, Journ. Agr. Res. 14 (1918) 151-175. Idem, A comparison of salt 
requirements for young and for mature buckwheat plants in water cultures 
and sand cultures. Am. Journ. Bot. 5 (1918) 186-191. 
