Dec., 1923 ] 
ALLISON AND SHIVE — GROWTH OF SOYBEANS 
557 
Fig. 1. Diagram of apparatus used for continuous renewal of nutrient solution. 
lary resistance and the elevation of the constant level above the outlet of 
the siphon thus formed. Any desired rate of flow can readily be obtained 
in this manner by a few trials. Experience has shown that these capillary 
tubes do not readily clog as do rubber tubes upon which metal clamps are 
set, and by their use a fairly uniform flow can be maintained with only an 
occasional cleaning. It should be noted that the main line C is composed of 
glass tubing having a bore of 4-6 mm. or larger, so as to avoid appreciable 
resistance to solution flow in this part. The more permanent parts of the 
exposed tubes were painted black to prevent the growth of algae. 
