‘ee 
LIBERATION OF ORGANIC MaTTrerR BY Roots oF GROWING PLANTS 31 
The movement of organic nitrogen from the plant into the soil solution 
yuld presumably be considerable, and possibly the cycle involving the 
sorption of nitrate nitrogen by the plant and its conversion into organic 
mpounds followed by a return to the soil of a part of these compounds 
da reconversion of the nitrogen into nitrates may be a very extensive 
e. What part it may play in the economy of the plant is at present 
ly a matter of speculation. It may be that the liberation of this material 
‘merely casual, while, on the other hand, it is conceivable that the 
bstances so eliminated are more or less injurious to the plant and when 
posed to the decomposing bacteria of the soil are destroyed and not 
vbsorbed. When liberated into a sterile solution they are not destroyed, 
d, being largely reabsorbed, they may exert a toxic effect on the plant, 
uch never makes a perfectly healthy growth in these solutions even 
ien it produces grain. 
TOTAL ORGANIC MATTER PRESENT IN NUTRIENT SOLUTIONS IN 
WHICH MAIZE PLANTS HAD GROWN 
The experiments previously described have dealt only with the forms 
nitrogen present in solutions in which higher plants have grown. It 
uld appear to be a matter of some interest to know something of the 
al quantity of organic matter in these solutions, and what proportion 
S organic matter may bear to the nitrogen present. For this purpose 
wumber of flasks containing the usual nutrient solution of one-tenth 
ength were prepared and maize plants were grown in these in the 
itomary way. It was planned to have a set of four flasks to be opened 
er the plants had grown for about two months, and another set of the 
ae number of plants to be harvested when fully mature. Unfortunately, 
| flasks in the latter set were all found to be contaminated when 
med, and for that reason the data furnished by these flasks are not 
isidered to be of value and are not included in table 3, which gives 
data for the first four flasks only: 
