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,’’ 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 beggiatoa—and another group, the cladothria, 
is capable of separating ferric oxide from water con- 
taining iron. 
Some light has been thrown upon the chemical com- 
