EXTENT OF BOOT-SYSTEMS. 



233 



Silver Fir 1 meter. 



Norway Spruce 2 meters. 



Scotch Pine 12 meters. 



All the plants upon which these averages are based were grown 

 under the same conditions. 



627. When any plant 

 is lifted, even with great 

 care, from the soil in 

 which it has grown, many 

 of its more delicate root- 

 lets are torn off and left 

 behind. Hence it is 

 difficult to ascertain the 

 total amount of roots 

 belonging to a plant. 

 Even the best plan yet 

 devised for cleaning the 

 root previous to measur- 

 ing it that of allow- 

 ing a stream of water to 

 wash awa}- all the earth 

 which it will detach 

 usually causes a few of 

 the finer rootlets to be 

 carried off. It has been 

 shown, however, that the 

 roots of peas, beans, and 

 the common cereals are 

 abundantly branched to 

 a depth of more than a 

 meter, and that many of 



them penetrate considerably further. Schubart states that the 

 amount, by weight, of roots in peas and wheat, compared with that 



b. LENGTH IN MILLIMETERS. 



FIG. 144. Roots of seedlings of Triticum vulgare. B, plant four weeks older than A. 

 The soil clings in <ach case to the younger parts. (Sachs.) 



