July, 1922] GERICKE ROOT DEVELOPMENT AND TILLERING 
of this element (nitrogen) may be compared to that existing in tap water. 
The wheat seedhngs grown in the nitrogen-poor soil developed a large 
root system after a period of several weeks. When nitrogen was added 
to these cultures, relatively large amounts of this nutrient were absorbed 
by the plant. This was more than was needed for the normal growth 
of the single shoots these seedlings had. The result from this treatment 
was a renewal and stimulation of vegetative growth. This gave rise to 
abundant tillering, which followed soon after the application of nitrogen. 
The cultures that received nitrogen at the time of planting obviously did 
not grow in a nitrogen-poor soil and consequently did not develop the 
same kind of root system as did those cultures grown in a nitrogen-poor 
soil. 
That the large root development in proportion to that of tops obtained 
in the cultures grown in tap water was primarily due to the deficiency 
of nitrogen, was further substantiated by the fact that this peculiar large 
root development was obtained with wheat seedlings grown in several 
different kinds of nitrogen-free ''nutrient solutions" prepared from different 
kinds of salts. This, however, does not mean that a nitrogen-poor medium is 
the only condition that may make for an abnormally large root develop- 
ment in wheat seedlings or in other plants. . 
It seems that the results obtained from these simple tests show that 
the extent of the root development of the wheat seedlings when nutrients 
are made available or become so is a matter of importance in the economy 
and culture of this important food plant. 
Laboratory of Soil Chemistry and Bacteriology, 
University of California 
