102 



KXPKNTMhJyrSl W fTH PLANTS 



a few moments in five per cent formalin and- then 

 rinse in clean water; heat the moist earth in the pan 

 (which should be covered during the operation) so 

 that it steams for ten or fifteen min- 

 utes; allow it to cool and then place 

 the seeds upon it. While the root- 

 hairs are growing, the glass cover 

 should not be disturbed. 



Does the amount of moisture affect 

 the luxuriance of growth of the root- 

 hairs? Use a series of pans, with 

 the soil varying from wet to fairly 

 dry. The seeds should be well 

 soaked when placed in the pans; the 

 moisture in each pan can be regu- 

 lated by lifting the glass cover so as 

 to permit greater or less circulation 

 of air. 



What is the use of the root- hairs ? 



The absorptive surface of the root is 



increased many fold by the root- 



_____ _ _ hairs. The long, feathery root-hairs 



85. Cutting of Wander- whlcll dcVClOD OU tllC rOOtS of CUt- 

 ing Jew in water, show- ^ 



ing root -hairs which tlugs of thc Waudcriug Jew placed 



increase the absorbing ^ <-" -^ 



surface from fifty to \^ watcr (Fig. 85) iucrcasc the root 



seventy -five times; in \ r> / 



:;?£ce'°wT.ho"rrZl surface from fifty to seventy - five 

 S:wr,'h"avetb: times; to get so much surface with- 

 taTameVer,"""'*" out the devlce of root-hairs eacli 



