18 -'T. L. Lyron ann J. K. Witson 
Fic. 2. OAT PLANT GROWN IN 
STERILE SOLUTION FOR 105 
DAYS 
(Table 1, serial no. 1272) 
present in the form of HNO;. (The quantity 
of soluble organic matter in the plant solutions 
was not great enough to interfere with the 
proper nitration of the phenoldisulfonic acid.) 
Ammonia was determined by direct ness- 
lerization. 
Organic nitrogen in the plant solutions was 
determined according to the method described 
by the American Public Health Association 
(1905). 
The total organic matter in the solutions 
was determined by evaporating 100 cubic centi- 
meters of the filtered solution and igniting the 
residue thus obtained at dull red heat. The 
loss on ignition was reported as organic 
matter. 
The dry weight of the deposit in the bottom 
of each flask was ascertained by transferring it 
to a filter, drying it at 110° C., and weighing 
it, the weight of the dry filter being subtracted 
from the total weight. 
The amount of organic nitrogen in the 
deposit in the bottom of each flask was found — 
by transferring the filter and contents from the 
previous determination to a Kjeldahl flask, 
digesting by the Gunning method, neutraliz- 
ing the excess acid with ammonia-free Na,COs, 
and - distilling off the ammonia, which was 
nesslerized. . 
TESTS FOR THE PRESENCE OF ORGANIC NI- 
TROGEN IN NUTRIENT SOLUTIONS IN WHICH 
PLANTS OF SEVERAL KINDS HAD GROWN 
Several different kinds of seeds were germi- 
nated under aseptic conditions, and were trans- 
planted, in the manner described, to flasks 
containing the usual nutrient solution of one- 
tenth strength. The manner of growth of the 
plants in these flasks is shown in figures 2 to 4. 
