150 
Journal of Agricultural Research voi. xxvii, No. j 
content coupled with decomposition of insoluble nitrogen. Under these 
conditions there was new growth, although there was no external supply 
of nitrates. As bearing on these relationships it may be pointed out that 
the relative capacity to effectively utilize carbohydrate for promotion 
of growth, the physiological translocation of plastic nutrients upward 
or downward in the plant, and the “reworking'’ of nitrogen and other 
plant-food elements present in limited quantities as a result of appro¬ 
priate change in the light period have been discussed in a previous 
paper {8, pp. 896 , 901) in so far as these phenomena are made evident 
by the observed responses of the plants. 
Biloxi soy beans were planted June 29 in the field and samples of leaves 
were collected at intervals of two to three weeks for determination of 
soluble carbohydrates and nitrogen in the cell sap. The plants began 
flowering September 12. The leaf samples consisted of sets of three 
upper full-size leaves of the plant. The samples were collected at 10.30 
a. m. The material was frozen and the sap expressed and filtered. To 
preserve the sap for sugar determinations, alcohol was added in quantity 
to form a 60 per cent solution after mixing, while for preserving the 
samples for nitrogen determination sulphuric acid was added to form a 
4.5 per cent solution after mixing. Reducing sugars were determined, 
before and after inversion with hydrochloric acid, according to the 
methods for foods and feeding stuffs of the Association of Official Agri¬ 
cultural Chemists. The nitrogen determinations were made according 
to the official Kjeldahl method modified to include nitrogen in nitrates. 
The results are shown in Table XIV. So far as may be judged by these 
data there is a slight increase in reducing sugar in the leaf at about the 
time flower buds are laid down, followed by a decrease during the period 
of unfolding the first blossoms. Three weeks after the flowering stage 
is reached, however, when seed development is well under way, there is 
a marked increase in reducing sugar and a small increase in soluble 
nitrogen. There appears to be little if any polysaccharid present 
in the sap at any stage. The data are not sufficient to justify 
final conclusion, but as far as they go seem to indicate that the most 
marked accumulation of soluble forms of carbohydrate and nitrogen in 
the leaf takes place after flowering has been initiated and during the 
active development of the fruit. 
Table XIV .—Sugars and nitrogen contained in 10 cc. portions of sap of Biloxi soy 
beans taken at intervals during the growing season. 
Date of sample. 
Reducing sugars. 
Nitrogen. 
Before in¬ 
version, 
(a) 
After in¬ 
version, 
(b) 
Difference. 
(b-a) 
July 26 . 
Gm. 
0.0934 
.103° 
.0750 
.0764 
. 1692 
Gm. 
0.0954 
. 1060 
.0786 
.0766 
.1764 
Gm. 
0.002 
.003 
.0036 
Gm. 
0.0219 
.0247 
.0226 
.0236 
.0290 
Ausr. 16. 
^^0* . .. 
Sept. 7... 
Sept 21 . 
Oct. 6... 
.0072 
Late-flowering Cosmos bipinnatus was planted in boxes out of doors 
on May 10. On August 5, when the plants were about 60 inches high, 
one lot was placed under a io-hour day. Under the io-hour day flower 
