-86 



FINE-STRUCTURE OF PROTOPLASMIC DERIVATIVES 



III 



pushing the cellulosic microfibrils apart by local plasmatic growth 

 (mosaic growth; Frey-Wyssling and Stecher, 195 i; Bosshard, 

 1952). 



Actually the insertion of additional cellulose microfibrils into the 

 existing fabric is not quite as difficult as it seems from the electron 



0.03(1 



Fig. 141. Cellulose frame in living cell walls (from Frey-Wyssling, 195 i). 



micrographs. The cellulose texture observed represents only 2.5 % by 

 weight of the growing cell wall; in the living state it contains 92.5 % 

 of water of hydration and only 7. 5 % of wall substances, of which 2/5 

 are pectins and hemicelluloses which are removed when the cells are 

 prepared for examination in the electron microscope. On the basis of 

 these figures and the known diameter of the cellulose microfibrils the 

 diagram of Fig. 141 has been drawn (Frey-Wyssling, 195 i), which 

 shows how much space is available for living cytoplasm [Christian- 

 sen and Thimann (1950) find 12 ^% protein in the primary wall of 

 pea seedlings] and highly hydrated accompanying substances in a 



