GETTING ESTABLISHED 



85 



upon the latter a funnel closed at the bottom with 

 a stopper; into this pour shot until the spring is com- 

 pressed to the same point as it was at the end of the 

 experiment. The weight of the funnel with the con- 

 tained shot gives the pressure exerted by the root. 



By preventing the root from bending, as suggested 

 on page 76, we could obtain much larger pressures. 

 Such a condition of things would occur naturally only 

 in a very firm soil. 



Another way to roughly test the power of the root 

 to penetrate the soil is to use a box with a bottom of 

 wire netting (the meshes being about five-eighths of an 

 inch square) . On the netting place cloths of various 

 thicknesses, tin-foil, slices of potato, or anything else 

 that the class may suggest. Fill the box with earth 

 and plant the seeds ; it may be easily observed if the 

 roots are able to penetrate any of these 

 objects; for this purpose hang the box 

 at a convenient height. 



What part of the root develops the 

 energy necessary for such strong growth ? 

 Remove some roots which are growing 

 in moist air (as shown in Fig. 78). 

 Mark them in the same way as you have 

 already marked the stem (Fig. 71). 

 Remove only one root at a time, mark 

 it arid place it as quickly as possible in water, where 

 it will continue to grow. Strong roots, such as those 



71. Root marked in 

 order to determine 

 the region of great- 

 est growth. 



