ISOLATION AND PROPERTIES OF WALLS 



A different kind of microstructure in a bacterial wall was 

 observed by Labaw and Mosley.^^ A rectangular array of 

 niacromolecules was found in the wall of an unidentified 

 organism. More recently, yet another type of fine structure 

 has been discovered in the wall of Lampropedia hyalina 

 from observations made by Dr. J. A. Chapman (Rheumatism 

 Research Department of the University of Manchester) and 

 the author and independently by Dr. R. G. E. Murray. The 

 outer layer of the wall of this organism possesses macro- 

 molecular subunits arranged to give the appearance of either 

 a honeycomb network or an array of "knobs" spaced on a 

 basal sheet— rather like a rubber mat. This type of struc- 

 ture gives rise to a "perforated edge" and lattice appearance 

 as seen in isolated cell-wall fragments (Fig. 6). 



In general, the niacromolecules or their spacings in the 

 fine-structured walls are of the order of 100 A. The diam- 

 eters of the large spherical niacromolecules of the Spirillum 

 sp. wall were 120 A.^^ 



Although bacteria such as Escherichia coli have shown 

 no fine structure in the isolated walls when examined in 

 the electron microscope by the usual methods, the thin sec- 

 tions prepared by Kellenberger and Ryter ^^ have clearly 

 established the multilayered nature of the wall. Thus, as 

 shown in Fig. 7, it has been possible to differentiate a multi- 

 layered wall from the underlying membrane (presumably 

 the protoplast membrane). As prepared for electron mi- 

 croscopy, the wall consisted of three layers, two of which 

 were electron dense and one electron transparent, each of 

 about 20 to 30 A in thickness. 



Thin sections of yeast ^^ and Chlorella pyrenoidosa 

 walls 2^ have also confirmed the presence of several layers; 

 they are probably double-layered structures. Thus, with 

 microfibrillar layers in their walls, the yeasts, Chlorella, and 

 some fungi closely resemble the wall structures found in 



