40 BOTANICAL GAZETTE [JANUARY 
H.0 HO : 
I |; } % 
10n/ 1000 t f 1on/ 1000 x iy 
i ae a 
2cn/1000 M 25n/1000 
Ol * \ r 
et se 
<on/I000 nf \ 50M, I000 K ri 
x i 
75n/1000 : 75#/ 1000 ey Ce 
ay Se 2 AL ton/ too ate) 
J ss ed oe ails 5 eee! 
25n/100 H# ty 25n/ 100 = 
a tao, - 
oa i oh | \ 
/ Fes iol cae ss f ies 
50n/ 100 vs — oa 50n/ 100 ” 
A PAF / 
75n/100 — 4 i 45n/100 F |}; 
9 4 ‘al ie 
e, pa eae es 
I 10 15 20 SS ic 5 10 
—aens ° 20 30 fon RS 550 750 950 * 
sees 50 ~ 450 650 Sa. = Se 110 aoe 
oes oa 7o 100 130 
. 34.—Alcohol series in solution. 
Fic. 33.—Alcchol series in soil. Mar. 2-22. 1906. 1606: 
re 2-22 
TABLE XXI 
ALCOHOL SERIES IN SOLUTION. MAaRrcH 2-22. 1906 
cy | SS SS) ee | ee a) ee n 
Ioc0 |) 1000 100 I 
Ay. length of rae ag Shing -|10.30 |10.85 {11.83 |13.35 |12.23 |10.96 | 9.43 | 6.66 | 4.81 | 3-49 
Total trans: ‘ 
Total green weigh’ } ey 
Total dry weight, mg 
WEY 877 | 910 | 1012 | 1109] 997 | 831 778 | 729 | 653 | 513 
See IIs 122 130 140 138 126 | 127 1oo | 97 95 
SUMMARY OF RESULTS 
Table XXII shows the concentrations in which growth in quartz 
soil and in solution is stimulated and inhibited. From this it will 
be seen that in soil, nickel is by far the most toxic substance tried, 
being nearly five times as poisonous as zinc, silver, copper, six to 
eight times as poisonous as iron, and forty to one hundred times 
as poisonous as alcohol. On the other hand silver in solution 
cultures is more poisonous than nickel, zinc, or copper, the ratios 
being as 1 to 5, 7, and 10 respectively; while with iron, lead, and 
alcohol the ratios are 1 to 100, 400, and 7500. 
It does not follow, therefore, that because a salt is highly toxic 
in solution it is equally so ia soil; nor that one which holds a rela- 
