394 BOTANICAL GAZETTE [MAY 
The initial H ion concentrations of the nutrient solutions 
were determined immediately before bringing the plant roots in 
contact with them. H ion measurements were then repeated for 
each solution throughout a time period of fifty-two hours, during 
which the solutions remained in contact with the roots of the 
growing wheat plants. Nine tests were made of each solution 
TABLE II 
FoRMULAE OF SOME LiviNcsTON-ToTTINGHAM (9) THREE-SALT NUTRIENT SOLUTIONS (TYPES I-VI) 
AND oF ToTriINGHAM’s (18) soLuTIoNs T,R,C; AND T;R,C; Moprriep (JONES AND SHIVE 6) BY 
SUBSTITUTING AMMONIUM SULPHATE FOR POTASSIUM NITRATE IN EQUIVALENT OSMOTIC CONCEN- 
TRATIONS; ALL SOLUTIONS HAD TOTAL OSMOTIC CONCENTRATION VALUE OF APPROXIMATELY 
1.00 ATMOSPHERE 
Volume-molecular partial concentrations 
Type _ ~ | KHzPO, | Ca(H:PO,)2 | Mg(H:PO,)2| Ca(NO;)2| Mg(NOs)2 | KNO, | MgSO,| CaSO, | KaSO, | (NH4)2SO. 
Livingston-Tottingham three-salt solutions 
I. | RsSa. .| 0.0072 0.0048 0.0072 olpeheceeate 
II. | RsS2 at 0.0019 0.0037 O.0094)-.+eeerer 
Tit. | R4S: 0.0025 ©.0099] 9.0074 iilnenie eee 
TV: Rr es 0.0019 ©,0057 0.0076|....000e08 
NV. | RaSe 0.0025 0.0074 0.0098]. ...c0efecererere? 
VI. | RaSz. .| 0.0093 0.0047 Oded esas ieee 
eS ae 
Modified Tottingham solutions 
T:RiCs) 0.0021 | 0.0073 | 0.0071 eh 0.0014 
T:RsCs| 0.0021 0.0073 | | | 0.0024] ....+- ohne 0.004 
during this period of contact. The small quantities of solutions 
withdrawn from the culture jars for the purpose of making tests 
were not replaced, since only about 2 cc. of solution was required 
for each determination. The H ion concentrations were deter- 
mined by the colorimetric method, using the double tube color 
standards described by GILLEsPIE (4). 
The formulae of the three-salt solutions given in table Il were 
selected from series of the six type-solutions proposed by LIvINGSTON 
and TorrincHam (9). One solution was selected from each 0 
six series to represent the six different types.2. The table also 
2 A detailed description of scp six type solutions, together with directions ei 
their preparation, may be foun 
m 
ents of representative agricult eal plants ey ti for a special Reuiaieine ne ae 
Division of Biology and Agriculture of the National Research Council.” Edited 
by B. E. Livincston, Baltimore. 1919 
