138 



FUNCTIONS OF CORK 



close connection between its cells. The frequent presence of 

 air in the latter retards excessive heating by day or excessive 

 cooling by night. Moreover, the waste substances commonly 

 encountered in the walls or cavities of the cork-cells are anti- 

 septic, excluding access of various parasites to the living tissues 



FIG. 66. Transverse section through the peripheral part of the stem of 

 the Currant (Ribes), showing the cork (Co.), the cork-cambium (C.C.), 

 and the extensive phelloderm (Ph.), of four to six layers of cells. 

 Beyond the cork are seen cortex and epidermis. 



within. As soon as cork-development commences, therefore, the 

 parts concerned become ensheathed in an almost impermeable 

 protective layer which would practically sever all direct com- 

 munication between the internal tissues and the atmosphere, 

 but for the formation of localised patches of loose tissue, the 



