May J9. 1916 Root Svstems and Leaf Areas of Corn and Sorghum 317 



at one end and provided with a wooden handle at the other was em- 

 ployed to make a passage through the soil block for the cross wires (PI, 

 XXXVIII, fig. 2). In the upper 2 feet of soil the cross wires were 

 pushed through the block of soil at inter\'als of 3 to 4 inches on both 

 the vertical and horizontal wires of the cage, while below that depth 

 they were placed at the intersections only of the vertical and horizontal 

 wires. In the isolation of the root systems of two mature plants, be- 

 tween 200 and 250 cross wires were pushed through the soil prism. 



vSeveral methods of washing the soil away from the roots were tried, 

 but the following was found the most desirable: The trench around the 

 block of soil was partially filled with water from an irrigation ditch near 

 by; and then by means of a pitcher pump connected with a ^-inch pipe 

 of convenient length the water was pumped into a piece of galvanized- 

 iron eaves trough and allowed to flow gently on the prism of soil (PI. 

 XXXVIII, fig. 3). In this manner the same water could be used over 

 and over again. As soon as any of the larger .roots were exposed they 

 were carefully tied to the cross wires so that they would not be moved 

 from their original position by the further washing. When the dirt that 

 had been washed from the soil prism had filled the trenches to the sur- 

 face of the water, the washing was discontinued and the water allowed 

 to soak away. The soil that had been washed into the trenches was 

 then removed, the trench again partially filled with water, and the wash- 

 ing continued. This routine, especially in working with mature plants, 

 had to be repeated several times. After the soil had been washed from 

 all the roots, the cages containing them were taken up, the unused cross 

 wires removed and the root systems studied and photographed. 



ISOLATION OF THE ROOT SYSTEMS FROM LARGE VESSELS 



The following method was used in the isolation of the root systems of 

 the plants that were grown in large galvanized-iron cans : 



As soon as the aerial portions of the plants were harv^ested, the soil 

 contained in the can was emptied upon a cleared space; and all the larger 

 roots were removed from the soil by carefully working it over, a handful 

 at a time. In order to separate the soil from the root particles still re- 

 maining in it, as much of the soil as possible was shaken through a sieve 

 with a -j^-inch mesh. In this manner all the finer root portions, together 

 with the larger soil particles, remained upon the screen. The root 

 remnants and the soil particles on the sieve were then placed in a vessel 

 and covered with a large excess of water, which was stirred vigorously 

 until all the lumps of soil had disintegrated. All the root remnants 

 floated to the surface of the water, and as soon as the soil in the vessel 

 had settled, they were removed by pouring the water upon the fine 

 sieve. All the roots which were obtained from each can were placed 

 upon the fine screen and washed carefully a number of times until, so 



