Appearance of cellulose microfibrils in the medium of a suspension of cells of Acetobacter
xylinum in buffered glucose solution was preceded by a stage during which the cellulose in
the medium was amorphous within the available resolution. The size of the vertical axis of
the microfibrils of the bacterial cellulose was found on the basis of measurement of shadow
length to be only about 16 A. In good agreement with findings of earlier workers, the size
of the lateral axis ("width") of the image of the metal-shadowed cellulose microfibrils was
found to be I 1 m/z. After correcting for a large part probably contributed by deposited
metal in the observed width of the microfibrils, the real width is estimated roughly to be
in the neighborhood of 3 m#. To account for the occurrence of diverse morphological
elements in the fields and for the fact that the cellulose fibrils are free entities rather than
physical appendages of the cell, it is suggested that individual cellulose molecules are released
at the cell surface and diffuse into the medium, wherein they finally enter into crystalline
patterns