(Vor. 7 
326 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
TABLE III—Continued 
Concentration Pa 
Cult. Total | Gr. wt. | Gr. wt. 
No. Salts used gr. wt. | tops | roots 
I I gms p s- |Init.| Fin 
1.0 gm. CaCO; 
.5 gm. Ca80, J-2H;0 
20 |1.0 gm. Sol. ferric phosphate I 19.15| 12.50 | 6.65 | 8.0| 7.9 
.5 gm. Mg:;(PO,)2+8H20 
40 ec KNO; 
21 Solution A 12.90| 7.92 | 4.98 | 4.1| 5.7 
22 Solution B 26.23| 15.16 | 11.07 | 6.6| 7.7 
23 Tottingham’s sol. 15.55| 9.20 |. 6.35 | 5.8| 6.4 
A relatively insoluble source of NH, (MgNH.PO,) has been 
found unsatisfactory as a source of nitrogen with the test plants 
used. 
In each of three series of cultures in which wheat or wheat 
and corn were used, one or more of the combinations containing 
two or more insoluble salts exceeded the growth in the best 
control culture employed. The best control culture contained 
CaSO,, MgSO., soluble ferric phosphate, and KNO,. Cultures 
exceeding the control contained in the several series the follow- 
ing combinations of salts: 1, CaSO, (solid phase present), Mg, 
(PO,)., soluble ferric late and KNO,; rr, CaSO, (solid 
phase present), MgN H,PO,, soluble ferric phosphate, and KNO,; 
nr, CaHPO,, Mg$O,, ferric citrate, and KNO, 
In all series, with the test plants mentioned, a group of cul- 
tures approached very closely the yields of the best combina- 
tions, and in all cases in such best combinations the calcium 
salt is relatively more soluble than the magnesium salt, except 
in certain combinations into which ferric citrate enters. 
Soluble ferric phosphate has proved a valuable constituent 
in the culture medium in a variety of combinations. In certain 
