THE GROWTH OF SACCHARIDE MACROMOLECULES 317 



action of levansucrase is easily available and can be expected to be a useful 

 aid for the elucidation of the intimate mechanisms of reactions in which 

 an interglycosidic oxygen bridge is concerned. 



Fig. I. An early reaction time in synthesis of cellulose by Acetobacter xylimini. 

 Cells were incubated in a droplet of glucose solution on a collodion film for 2 min. 

 Product was freed from non-polymeric solutes in the extracellular phase by flotation 

 on water. A typical intercellular space is shown. There is an abundance of a poly- 

 meric material in the form of granules, rods and branched processes extending 

 from slimelike regions. At zero time of reaction the space was optically empty. 

 Pt shadow-cast (shadow ratio i :5). Magnification x 50 000. (Electronmicrograph 

 prepared by Dr. D. Danon and Air. I. Ohad.) 



Growth of cellulose fibre in an extracellular phase 



Synthesis of cellulose in Acetobacter provides an example of a poly- 

 merization system in which, as in the case of the production of levan and 

 dextran by cells, the accumulation of polymeric product occurs in the 

 extracellular phase. In the case of cellulose production, unfortunately, 

 even the general nature of the reaction mechanism remains obscure. 



Greathouse [5] has reported that an ATP-fortified homogenate of 

 A. xylinum cells readily synthesizes cellulose. Stacey [6] has reported, on 

 the other hand, that attempts to duplicate this result have failed. Dr. 



