THE GROWTH OF SACCHARIDE MACROMOLECULES 



321 



should be noted, however, that a detailed examination of the results does 

 reveal a quantitative deviation in some of the data from values that would 

 be predicted on the basis of the conventional scheme of the pentose cycle. 

 This implies, as indeed can readily be assumed, that hexose phosphate in 

 the metabolic pools of this cell is probably involved also in additional and 

 perhaps still undefined metabolic transformations. 



Fig. 4. Cellulose pellicle formed from glucose in a relatively concentrated 

 suspension of cells of Acetobacter xylimmi. Cells are enmeshed in a cellulosic 

 film which consists of fibres running through relatively amorphous regions of 

 pol>Tner. Ultrastrands are resolvable in the fibre regions. Granular matter con- 

 stitutes the amorphous phase. Specimen, which was freed from non-polymeric 

 solutes by flotation in water, is mounted directly on a copper grid. Pt shadow-cast 

 (shadow ratio i :5). Magnification x 25000. (Electronmicrograph prepared by 

 Dr. D. Danon and Mr. I. Ohad.) 



The Acetobacter enzyme-system which converts hexose phosphate into 

 cellulose is known to be anchored to the cell. Since the formed cellulose 

 fibre is observed in the extracellular medium as a free entity rather than 

 as a physical appendage of the organism, we may assume that the mor- 

 phological precursor of the fibre is a diffusible cellulose form — probably 

 a lone cellulose molecule — which escapes from the cell into the medium 

 wherein it finally enters into a crystalline fibrous habitat. 



