Chibnall.—Diurnal Variations in the 
516 
Table IV. 
Showing the Fall in the Nitrogen Content of Leaves of Various Plants 
at Night , expressed as a Percentage of the Day Value. 
(Suzuki) 
Name of Plant. 
Method A. 
Alethod B. 
Wisteria brachybotrys (400) 
13.6 
- 1*45 
Phaseolus vulgaris (50) 
4-3 
0-0 
,, 7 nungo (200) 
10-9 
— 2.24 
Pueralia Thunbergiana (51) 
4.8 
1 -39 
Solanu?n tuberosum (220) 
8.4 
— 28.2 
Batatas edulis ( j 00) 
4.0 
-i -33 
Polygonum fagopymwi (450) 
«*3 
— 3.82 
Helianthus a 7 inuus (33) 
97 
— 2.09 
Sufficient details are not given for the fall by Method C to be calculated. 
Futhermore there is no mention that any regard has been paid to sampling 
errors. In view of the percentage error of 4*5 quoted above for Vicia Faba 
Suzuki’s results by Method A must be considered inconclusive. It will be 
noted that Method B shows in most cases a gain at night, probably indi¬ 
cating nothing more than a large translocation of sugars. 
Kosutany (6) has taken a series of diurnal readings for the nitrogen 
content of the leaves of Vitis riparia. The vine was so placed that it was 
in the shade after 2-3 p.m. At 3 p.m. one-half of a certain number of 
leaves was removed by cutting alongside the mid-rib, the other half being 
removed at 3 a.m. the following morning. He expressed his results by 
Methods B and C (summarized in Table V), but drew all his conclusions 
from the former. 
Table V. 
Shoiving the Fall in the Nitrogen Content of the Leaves of Vitis riparia 
at Nighty expressed as a Percentage of the Day Value. 
(Kosutany) 
Date picked. 
Method B. 
Method C. 
4-5 J une 
-1.15 
0-0 
19-20 June 
— 2-80 
7-68 
3-4 July 
—1.62 
- 5-99 
14—15 Aug. 
-1.66 
— 0.71 
28-29 Aug. 
—1-42 
7.84 
25-26 Sept. 
-2.03 
4-86 
9-ic Oct. 
-2.74 
4.20 
He therefore stated that leaves became enriched with nitrogen during 
the night, and concluded, from further analyses, that this was due to the 
accumulation of protein. In light of the discussions given above it will be 
seen that this conclusion is not justified. By Method C there is in four 
cases a fall, in one no change, in one a very small rise, and in one only any 
evidence of a pronounced rise. 
