358 Jones and Skive.—Influence of Ammonium Sulphate 
as do other forms of soluble iron. By direct qualitative tests it was found 
that the iron added to the nutrient solutions in this soluble form was not all 
precipitated seven days after it had been added. The precipitation of this 
soluble iron is attended with a slight increase in the H-ion concentration of 
the culture solution. 
Table I. 
Description of solutions used. 
Partial volume-molecular concentrations 0 
Solution. Ammonium-sulphate series ( B ). 
No. _.__ 
Tottingham series ( A ). 
___j>- 
kno 3 . 
Kl/ 2 PO i . 
Ca(N0 3 ) 2 . 
MgSO 4 . 
{NHi\SO±. 
w t 
0-0020 
0-0021 I 
0-00146 
0-01659 
0-0014 
c 3 
0.0020 
0-002 II 
0-00438 
0-01185 
0-0014 
C 5 
0-0020 
0-0021 I 
0.00730 
0-00711 
0-0014 
C 7 
0-0020 
0-00211 
0-01022 
0-00237 
0-0014 
RA 
0-0060 
0-002 11 
0-00146 
0-01185 
0-0042 
c 3 
0.0060 
0-002 11 
0-00438 
0-00711 
0-0042 
C 5 
0-0060 
0-002 II 
O.OO73O 
0-00237 
0-0042 
R 5 Cx 
0-0100 
0-0021 I 
O.OOI46 
0-00711 
0-0070 
C 3 
0-0100 
0-002 11 
0-00438 
0-00237 
0-0070 
R7C1 
0-0140 
0-002 11 
O.OOI46 
0-00237 
0-0098 
TsRxC, 
0-0020 
O.O0633 
O.OOI46 
o-oi 185 
0-0014 
C 3 
0-0020 
0-00633 
0-00438 
0-00711 
0-0014 
C 5 
0-0020 
0-00633 
0-00730 
0-00237 
0-0014 
R 3 Ci 
0-0060 
0.00633 
O.OOI46 
0-00711 
0-0042 
c 3 
0-0060 
0-00633 
- 0-00438 
0-00237 
0-0042 
R 5 Cx 
0-0100 
O.O0633 
O.OOI46 
0-00237 
0-0070 
t 5 RA 
0-0020 
0-01055 
0-00146 
0-00711 
0-0014 
c 3 
0-0020 
O.OIO55 
0-00438 
0-00237 
0.0014 
r 3 a 
0-0060 
°- OT °55 
0-00146 
0-00237 
0-0042 
0-0020 
0-01477 
0-00146 
0-00237 
0-0014 
The Edna variety of soy bean, Soja max , was used throughout the 
different experiments. The seeds were germinated either in washed sand 
or sphagnum moss. When germinated in the sand it was necessary to 
incinerate the roots to obtain their dry weights, the loss of weight upon in¬ 
cineration being taken as the weight of the roots. Uniform seedlings were 
selected when the cotyledons were opened sufficiently to determine the 
presence and uniformity of the unopened plumule. Three seedlings were 
comprised in each culture and were mounted in the double-piece paraffined 
cork stoppers as devised by Tottingham. These were of proper size to fit 
the quart fruit jars of colourless glass which were used as solution con¬ 
tainers. Manila paper cylindrical shells, black within and light on the 
outside like those described by Shive ( 36 ), were used to exclude light from 
the cultures and prevent heat absorption. 
The solutions were renewed regularly at intervals of three and one- 
half to four days. After each interval the solutions which had been used 
were tested for their hydrogen-ion concentrations. This was done by 
1 Total osmotic concentration value of each solution, i atmosphere. 
