1922] JONES & SHIVE—WHEAT SEEDLINGS 395 
contains the formulae of ToTTiNGHAm’s (18) solutions T,R,C, and 
T,R;C, modified (Jones and SHIvE 6) by substituting ammonium 
sulphate for the potassium nitrate in equivalent osmotic con- 
centrations. It has previously been shown (6) that in the Torrinc- 
HAM solutions when thus modified, the direction of the reaction 
change induced by contact with the roots of young wheat plants 
is usually the exact opposite of that in the unmodified solutions. 
It was because of this fact, and also because these modified solutions 
are capable of producing excellent growth of young wheat plants, 
that they were included in the experiment. 
Discussion 
The initial Py values of the nutrient solutions, the formulae 
of which are given in table I, and the Py values determined at 
intervals during the period of fifty-two hours throughout which the 
solutions remained in contact with the plant roots, are given in 
table III. It will be observed from the data of this table that the 
TABLE UI 
Py VALUES OF NUTRIENT SOLUTIONS DETERMINED AT thecoagpa DURING CONTACT 
WITH ROOTS OF GROWING WHEAT PLAN 
P,, VALUES 
AUTHOR OF SOLUTION Duration of intervals in hours 
3 Inr- 
TIAL 
2 4 1 0.5 ees) af 10.5) 33] 58 
peo tn Lenn. 4:41 4.8 146. 1 4.71 28-1 6.9 1 5.0 1.2 | 5-3 1 58 
Sa iach vean poo 6.6 | 6.7 | 6.6] 6.5 | 6.5 | 6.5 | 6.5 | 6.5 | 6.5 | 6.6 
aes stella 4-7] 4-8] 4.9] 5-0] 5-2] 5-6] 5-6] 5.7] 5-7] 5-9 
Hartwell ee and 
PO os AO VAO PALE 145.4 4-4 427.4 4-7-1 560 1 5-3 . 
i CE prenisouine: Sg 4.6 14.7 1.4.8.1 §-0 1-8-2 1 5.3.5 5-3.1 5-4 1.5:5 -7 
EEE, 4.9 O71 AO | BE 1 BES] S51 S51 5-5 | 8:7 1 8-8 
SOON fo oii vins dase 6.7} 6.8] 6.6] 6.5 | 6.5 | 6.5 | 6.5 | 6.5 | 6.5 | 6.6 
ton, 1 fe Mano ea 4.8 | 4:01 5-2 | 5-2] 5-4] 5-7] $7] 5-8] 5-9} 6.x 
talaga cpm 4.2|4.214.4| 4-4] 4.6] 5.41 5.5 15-7] 5-9 | 6.1 
mnie, RAG, 4.5|4.6|4.6| 4.6] 4.7] 4.8| 4.8] 5.0] 5-1 | 5-3 
oem. 46165142601 6.21 $515.5 1 5-51 §-6 | 5-9} 5.9 
Tottingham, T,R,C,..| 4.6 | 4.7 | 4.8 | 4.9 | 5-0 | 5-2 5-2 | 5-3 | 5-4) 5-5 
initial Py values of only two of these solutions are close to the 
neutral point. CRONE’s (2) solution has an initial Py value of 6.6, 
_ and Sacus’s (13) solution has a corresponding initial value of 6.7. 
