BACTERIOLOGY. 



PART I. 



CHAPTER I. 



MORPHOLOGY OF BACTERIA. 



Description: Bacteria are minute unicellular vegetable 

 organisms which resemble an ordinary tissue-cell. They 

 belong to the fission-fungi, a subdivision of the Thallophytce, a 

 class of the Oryptogamia. They differ from lichens and algae 

 in that they contain no chlorophyll and live only on organic 

 matter. 



The fission-fungi are divided into : 

 SCIJJZOM YCETES ba cteria. 

 HYPHOMYCETES moulds. 

 S ACCRA ROM ~YCETES yeasts. 



All bacteria possess a limiting cell-wall or capsule, which 

 encloses a homogeneous or granular cell-protoplasm and a 

 nucleus. 



This protoplasm consists principally of an albuminous sub- 

 stance known as mycoprotein. The chemical formula of this 

 proteid substance is C 25 H 42 N 6 O 9 . 



Water and salts also enter largely into the chemical com- 

 position of bacteria. One group, the Beggiatoa, a higher 

 species of plant, contains in addition sulphur granules. When 

 grown on culture-media, the composition of bacteria is subject 

 to variations depending upon the kind of media used. 



The anilin dyes, which are used almost exclusively for 

 staining bacteria, stain the organism uniformly so that the 

 nucleus is obscured ; but when special nuclear stains are used, 



2 Bact. 17 



