SURFACE STRUCTURES 4I 



E: THE SPORE COAT 

 (23,60,81,82) 



The resistance of the bacterial spore to inimical agencies has been attributed 

 by some authorities to the impermeable spore coat, and by others to the 

 peculiar condition of the cytoplasm of the spore. 



While the spore coat is difficult to stain, it is no more so than the cell wall 

 of vegetative bacteria, from which it docs not appear to differ markedly in 

 any respect. Like the cell wall, the spore coat may be partially destroyed by 

 hydrolysis with hydrochloric acid, and it is probably composed mainly of 

 polysaccharide material. 



Electron micrographs ot sections ot spores have shown that the spore coat 

 is a single structure in Bacillus ccrciis, whereas in B. iiwoatciitini at least two 

 layers can be discerned (Robinow, 1953). 



The ejection of the turgid nuclear material from hydrolyscd spores indicates 

 that the spore coat possesses a small area ot weakness, possibly a germination 

 pore. 



F: THE NUCLEAR MEMBRANE 

 (5, 13, 14, 30) 

 The apparent absence of a nuclear membrane in bacteria has many times 

 been remarked upon in cytological literature. This is probably due to the 

 fact that bacteria have been examined mainly in their period of active, 

 vegetative growth, when the nucleus is permanently in the chromosomal 

 condition. The resting nucleus has a membrane ot normal appearance. 



Electron micrographs of sections ot bacterial nuclei have shown signs ot 

 a fibrous layer surrounding the denser portion of the nucleus. 



G; SLIME LAYERS AND CAPSULES 

 (34, 56, 88, 92, 93, 94, 95, 96, 97, 98) 

 Many bacteria possess a surface layer of mucoid material, and occasionally 

 a well-defnied capsule. The two structures have often been confused, but 

 ' are distinct and may be found simultaneously. 



