82 Brenchley. — Effect of Concentration of the Nutrient Solution 
With all other concentrations the march of events was delayed, but not 
arrested. Considerable improvement occurred immediately after the change 
(the weaker the solution the more obvious the improvement), but the falling 
off in growth soon reasserted itself in each case, though the ‘ fillip ’ caused 
by the renewal of the food supply was well reflected in the dry weights (see 
Table I and Curve I). 
Series i. March 15-May 3. 
Solutions changed 
Solution . 
1 
Frequently . 
1 
Once . 
1 
Never . 
Shoot . 
Root . 
Total . 
Shoot . 
Root . 
Total . 
Shoot . 
Root . 
Total . 
N 
N/o 
N/io 
N/20 
/ 
2-919 
2-608 
1-984 
1-303 
1-082 
1-041 
0-816 
0-528 
4-001 ± 0-142 
3-649 + 0-074 
2-800 + 0-049 
1 -83 1 ±0-038 
2-639 
1-483 
0-791 
0-447 
0-713 
o -543 
0-447 
2-289 
3-35 2 ±0-096 
2-026 ± 0*07 2 
1 -238 ± 0-048 
0-736 ± o-ooi 
I -897 
0-958 
0-526 
0-244 
o -735 
0-446 
0-301 
0-208 
2-632 ±0.071 
i*404±o-o20 
0-827 ±0-015 
0-452 ±0-011 
Series 2. April 5-May 24. 
Solutions changed 
Solution . 
1 
Frequently . 
1 
Once . 
1 
Never . 
Shoot . 
Root . 
Total . 
Shoot . 
Root . 
Total . 
Shoot . 
Root . 
Total . 
N 
4-442 
i- 33 o 
5 ' 77 2 ± 0-193 
3-746 
1-324 
5'07°±o-209 
3-048 
1 - 1 59 
4-207 ±0-113 
N /5 
3-365 
I * I 37 
4-502 ±0-076 
1-621 
0-709 
2 - 33 o±o-ii 7 
1-136 
0-631 
1 *767 ± 0-037 
N/io 
1-899 
0-843 
2-742 ± 0-097 
0-841 
0-470 
1-311 ± 0-056 
0-525 
0-409 
0-934 ± 0-040 
N/20 
1-283 
0-683 
i-966±o-042 
0-363 
0-318 
o- 58 i ±0-025 
0-253 
0-258 
q-5 11 ±0-015 
Series 3. April 26-June 14. 
Solutions changed 
Solution . 
1 
Once . 
1 
Never . 
Shoot . 
Root . 
Total . 
Shoot . 
Root . 
Total . 
Shoot . 
Root . 
Total . 
N 
5-137 
1-320 
6*457 ± 0‘ J 44 
3-218 
1-400 
4-618 ± 0-117 
2-401 
1-293 
3*694±o-ioi 
N /5 
4-574 
1 '467 
6-041 ±0-124 
1-841 
0-804 
2-645 ±0-067 
0-922 
0-690 
i-6i 2 ±0-080 
N/io 
2-286 
0-806 
3 -o 92 ±o-i 75 
■0-428 
0-220 
0-648 ±0-032 
0-285 
0*233 
0-518 + o-o 1 1 
N/20 
i -254 
0-527 
1-781 ± 0-074 
0-179 
0-113 
0*292 ± 0‘OIO 
0-085 
o-o8i 
o-i66±o-oi5 
Table I. Mean dry weights in grams of ten barley-plants grown 
in nutrient solutions of various strengths. 
