THE WALLS OF PLANT CELLS 



33 



Fig. 5. Expanded transverse set-tion of a concentrically lamellated secondary wall. Total magnifica- 

 tion, x 11,000. 

 Fig. 6. Expanded transverse section of wall having a ramifying structural pattern. Total magnifica- 

 tion, X 7150. 

 Fig. 7. Frey-Wyssling 's conception of the submicroscopic structure in transverse and longitudinal 



sections of cellulose. Micelles are light, intermieellar spaces are dark. 



Fig. 8. Surface view of an early stage in the formation of the secondary wall of cotton, showing 



coalesced fibrils and a "reversal" in their orientation (xllOO). After Kerr. 



