406 BOTANICAL GAZETTE [DECEMBER 
An answer to the second question must also be given as a hypothesis. 
The large root development of the wheat seedlings placed in tap water 
did not result in the production of large wheat plants. The roots 
grew at the expense of the tops. Obviously wheat shoots could not 
have grown to any appreciable extent without roots, so between the 
two limits thus indicated (no roots on the one hand, and one-half of the 
total dry matter being roots on the other hand) must be found that 
relation of root to top that will bring about the best growth of the wheat 
plant. 
Fig. 1 shows the relative root development of two different cultures, 
with approximately similar top growth. One was grown in tap water 
for six weeks and produced roots over 100 cm. long, the root mass being 
about six times longer than the length of the tops. The other culture 
was grown in a good nutrient solution for two weeks and produced 
roots that were only a trifle longer than the length of the tops. Approxi- 
mately this same ratio of length of root to that of top would have been 
maintained if it had been grown six weeks or longer in this good nutrient 
solution.—W. F. Gericke, Division of Soil Chemistry and Bacteriology, 
University of California. 
