CHAPTER II. 



THE CHEMICAL COMPOSITION OF BACTERIA THE 

 CONDITIONS SUITABLE FOR THEIR GROWTH. 



Chemical Composition. Qualitatively considered, the 

 bodies of bacteria consist largely of water, salts, fats, 

 and albuminous substances. There are also present, 

 in smaller quantities, extractive substances soluble in 

 alcohol and in ether. According to Cramer, there is 

 no grape-sugar found in any bacterial species, but many 

 bacteria contain amyloid substances which give a blue 

 reaction with iodine. True cellulose has been found in 

 the bacillus subtilis and an organism closely allied to 

 the bacillus coli; the tubercle bacillus also forms cellu- 

 lose in the animal body, though no cellulose has been 

 found in cultures of the tubercle bacillus. But from 

 these and from cultures of a " capsule bacillus from 

 water/ 7 allied to the pneumococcus of Friedlander, 

 large quantities of a gelatinous carbohydrate similar 

 to hemi-cellulose have been obtained. Nuclein, first 

 demonstrated by Vanderville, is only found with diffi- 

 culty; but the nuclein bases xanthin, guanin, and 

 adenin have been found in considerable amounts. 

 There is a group of bacteria which contain sulphur 

 viz., the begyiatoa and another group, the cladothrix, 

 is capable of separating ferric oxide from water con- 

 taining iron. 



Some light has been thrown upon the chemical com- 



