4 



ROOT-HAIRS. 



Root-hairs are continuations of some of the outer cells of the 

 younger roots and are brought into very close contact with the 

 particles of soil. Their number depends much on the nature 

 of the medium in which the roots are grown. Where the soil is 

 rich, moist and porous, root-hairs are abundant. They are very 

 short-lived, often lasting only for a few days, new hairs from 

 other rootlets taking their places. 



The upper and. 

 older portions of the 

 roots merely serve 

 to hold the plant in 

 position and act as 

 conductors for the 

 trans mission of 

 matter to the leaver 

 of the plant and 

 some of it back 

 again to the newer 

 roots. The reader 

 should consult fig- 

 ure 2, representing 

 a young wheat plant 

 carefully lifted with 

 the sand which is 

 held fast by its close 

 contact with the 

 root-hairs. The 

 tips of the roots have 

 not put forth hairs- 

 and hence they are 



Fig. 3. — Roots of young Fig. 3.-Plant a little older still naked, 



wheat plant lifted from the with soil clinging to the 



soil, holding soil by the root- younger parts, but not to Fio"Ure 3 reprC- 



liairs excepting near the the <il(icr parts as there the '^ ^ 



apex where tlie hairs have root-liairs have perished. 

 not yet been produced. 



sents the roots of a 



