76 



BOTANY OF THE LIVING PLANT 



the growing hair, and the dehcate cell-wall is lined by a thin him of 

 cytoplasm surrounding a central vacuole. A gummy softening ot the 

 wall near the distal end leads to a most intimate connection with any 

 solid particle. The state of the root-hair in the soil is suggested by 

 Fig. 57. As the water in the soil is held in the form of surface films 



Fig. 58- 

 Seedling of Carpinus Betiilus. h — 

 hypocotyl. c = cotyledons. /r(i' = main- 

 root. S'c£'=lateral roots. r = root-hairs. 

 c=epicotyl. / = foliage leaf. Natural 

 size. S. 



oy 



Fig. 59. 

 Localisation of growth near to the root-tip 

 of Vicia Faba. In I. the root-tip has been 

 marked with 10 zones i mm. apart. In II. 

 the same root after 22 hours. The Unes 

 nearest the tip are now most separated owing 

 to the growth having been there most active. 

 (After Sachs.) S. 



covering the several particles, the root can by its hairs tap those hlms, 

 however thin they may be in a dry soil. It is important further to 

 realise how numerous these root-hairs are. It has been estimated 

 that over two hundred of them may be borne on one square 

 millimetre of surface of the root of a Pea, while in other plants, for 

 instance the Maize, the number may be still higher. The effect of 

 this is greatly to increase the possible absorptive surface of the root. 



I 



