30 BACTERIOLOGY FOB NURSES 



free oxygen, called oblipatory anaeroh esj and (3) the 

 facultative an a^ obes, which may p yif jt. with ny wit Vi- 

 out_02c^geiL. 



The obligatory anaerobes derive the small amount 

 of oxygen necessary to them from the oxygen com- 

 pounds of the material in which Jihey are growing. 



Food. — Bacteria obtain their food from many 

 diverse substances, organic compounds of all kinds 

 serving them. Nitoogen ous substances _e sp£cially 

 are quicMy attacked , by manyi^pecies, as may be 

 witnessed in the rapid decomposition of meats. 



Ca,rhon. nitrogen, and wa,ter are Rsspntial for t,h f> 

 j ;rowt.h nf both ba.cteria a.nd the higher plants , but 

 in the case of the latter both carbon and nitrogen 

 must be resolved into simpler forms before absorption 

 can take place ; while bacteria obtain these elements 

 as already prepared in complex organic material, 

 either animal or vegetable. 



Bacteria differ greatly in their food requirements, 

 some species thriving best upon a concentrated form 

 of nourishment, and others requiring only a limited 

 amount of protein substances. 



The greater number of bac jg ria belon g to thg class 

 known as ,in.prnphytp.R, wyuoh find thfiir f ood in dead 

 Qgganic _ matter, and^cannot exists in_Uyin£_dsgues ; 

 goragiteSi on the contrary, as the name indicates. 



