Oct., 1922] TURNER EFFECTS OF CERTAIN MINERAL SALTS 429 
than occurred in Experiment I. These conditions are taken to account 
for the unsteadiness of growth which is shown from a study of the actual 
dry-weight values, as well as from a study of the magnitude of the probable 
errors of the mean ratios of tops to roots which have been computed in 
each case. The results of the four series of Experiment II are given in. 
table 5. 
It will be remembered that the low-nitrate solution now contains 
3,075 p. p.m.; the medium-nitrate, 1,350 p. p.m., and the high-nitrate, 
1,860 p. p.m. The ratios of tops to roots do not appear to be affected ap- 
preciably by the concentrations of the solutions; for in this experiment we 
have not simply the reverse conditions as to concentration, but the total 
concentration of the low-nitrate solution is now nearly 5 times its former 
value, yet results obtained throughout the four series are uniformly com- 
parable to those obtained in Experiment I. The significance of the data 
obtained in this experiment is clearly shown from a study of the differences 
of the means of the ratios of the different solutions, taking into consideration 
the probable errors (table 5). Concentration as such, therefore, has shown 
no effect upon the ratio of tops to roots. 
Growth Features 
Root growth of cultures in Solution la (3,075 p. p.m.) was of a different 
character from that in the two other, less concentrated solutions. The 
roots are much shorter, more turgid, and the individual fibers are greater in 
diameter. Data for length of tops and roots taken for the first three series 
are as follows: 
Sol. la 
(Low Nitrate) 
Sol. II 
(Medium Nitrate) 
Sol. Ilia 
(High Nitrate) 
Series i 
Series 2 
Series 3 
Tops 
Roots 
Roots 
Tops 
Roots 
15.2 cm. 
7-75 " 
37.88 " 
9.28 " 
40.9 " 
II. I " 
18.3 cm. 
16.0 " 
34-25 " 
18.5 " 
39-5 " 
19. 1 " 
16.2 cm. 
16.2 " 
34-5 " 
19-5 " 
41.6 " 
17.0 " 
The length of tops continues about the same during these three series. 
No differences were observed as to health and vigor of these cultures, so the 
effect of this more highly concentrated solution seems to be shown in 
bringing about a change in the morphological character of the root. Since 
the growth values in this solution relative to the medium-nitrate solution 
(which is the same as that used in Experiment I, both as to nitrate con- 
centration and as to total concentration) and in Solution Ilia are practically 
the same as they were where we had the reverse concentration conditions, it 
would seem that the physiological processes underlying this change are 
of a different order and, being within the root itself, do not affect the ratio 
