Water-Content of Plants 43 



trated mass upon a support or screen closely studded with 

 nails. Upon this screen careful washing is subsequently 

 given, and the entire root-system is then readily transferred 

 to cardboard. Figure 9 shows a root-system of the potato 

 grown in this manner. About 30 plants were grown by 

 Rotmistrov in such boxes for varying periods of time. 



As a control upon this method some plants were grown 

 in natural soil beds, and the development and extension of 

 the root-systems were studied by means of deep pits with 

 horizontal chinks or tunnels. The pits permitted a care- 

 ful record of the depth of root extension, and through the 

 small horizontal chinks observation could be made upon 

 lateral penetration. 



Working with the pit-and-chink method indicated, it 

 was determined that even in seven days the roots of " a 

 great many cultivated plants extend beyond the limits of 

 the soil when tilled to a medium depth " (8 inches). The 

 roots of winter grain often extend laterally and vertically 

 to a distance of over 40 inches. Winter rye was found to 

 extend to a greater depth, and winter wheat to a greater 

 extent laterally, than other small grains. 



Among the roots of corn there may be distinguished, 

 according to Ten Eyck, primary vertical and primary 

 lateral organs. The latter in their course again give off 

 vertical roots. The main laterals grow several feet, and 

 as they reach those of neighboring hills, they also strike 

 downward. Under the rather dry conditions of the AVest 

 a majority of the lateral roots are within from three to 

 twelve inches of the surface. When the sub-soil is poor, 

 deep culture of corn may therefore kill the roots or prevent 

 their formation in the most fertile parts of the soil. On 



