RECORD OF THE EXPERIMENTS tT 
a luxuriantly developed root system with vigorous laterals. The 
intermediate cultures showed a perfect transition between these two 
conditions. The significant cultures from experiment C are shown 
in figures 1 to 8. The condition of the roots when photographed was 
as follows: 
No. 4 (aug Me(NO;).). Primary dead; no laterals.!. (Fig. 1.) 
ee B! M ; Seni: : . va =e hse 
No. 5 (50,000 “£+ 50,000 Ca). Hardly different from No. 4in appearance, but alive. 
98 M 2M 
= Meg Ca). Primordia of laterals beginning to show, but otherwise 
50,000 !8+50,000 ©? a : 
nis Mo a). Simils oP 
No. 7 sete 0. Ca). Similar to No. 6. 
- 96 M 4 = ‘ a i 
No. 8 (50,000 000 Mg 50 Laterals manifest. (Fig. 3.) 
i" 
No. 9 (= 000 ee - vo ME+so; “ae Ca). Laterals several millimeters long; condition of root 
M = 
system very similar to that of No. 3 (~ 10,000 Mg (NQ3),). 
\ \ 
No. 10 (000M ee : Ca). Laterals more numerous and somewhat longer 
than in No. 9. (Fig. 4. ) 
N \ : es oe 
ee | (000 M 850,000 Ca). Three seedlings as in No. 10; one as in No. 12. 
e 5.) 
ARS = ae eae ote Ca). With this ratio of magnesium to calcium the root 
50, 000 > Ig 50,000 ~*’* ais ; 
system begins to present a normal appearance. The laterals in distilled water (cul- 
= : M é : : : 
ture No. 1) and in 50.000 Mg (NO,), (No. 2) reach a state of development intermediate 
between that attained in Nos. lland 12. (Fig. 6.) 
M \ ; 
43 000» fe+59-900 a Ca). Similar to the last. (Fig. 7.) 
N 
No. 14 (ean Me+55 000 : Ca). Root system perfectly developed. (Fig. 8.) 
Conclusions which can be drawn from experiment C are: (1) 
That the maximum ratio of magnesium to calcium which permits 
a normal root development in solutions of the two nitrates alone 
M 
500 
9 : : : 
is about =; (2) that magnesium nitrate in concentration has 
M 
1’ 50,000 
about the same effect on the roots as distilled water; (3) that 
) | , | 
10, — Mg (NO,), is approximately the most concentrated solution 
of this salt which permits the development of laterals. 
1 The short laterals shown just below the cotyledons in figures 1 to 8 were not developed in the culture 
solution, but in the moist air of the bore through the paraffin supports. They may be distinguished by 
their contorted growth from the long divergent laterals grown in the solutions. 
9427°—Bul. 231—12 3 
