CKNKRAL COXSIIIIiKATKIN OK 1)1 SI-IASE. :)/ 



of small granules in the protoplasm of the parent cell. These 

 granules collect and ultimately coalesce thus forming the spore. 

 The spore may form in the center of the bacterium or near one 

 end. After the spore is formed the remainder of the bacterial 

 body becomes disintegrated. Spores are much more resistant 

 to external injurious influences than are bacteria. The resist- 

 ance of spores is due to the fact that tlun- contain less water 

 than bacteria, moreover they enjoy the protection of a thick 

 covering or cell wall. Spores are inactixe, i. e., they remain dor- 

 mant until placed in favorable media and under fa\iiral)le con- 

 ditions when thev germinate and develop as the vegetative 

 form. One bacterium produces only one spore which in turn 

 produces onlv one bacterium and hence spore formation is not 

 a means of nniltiplication, but is rather a natural means of pre- 

 servation or continuation of the species. Those species of 

 bacteria in which no spores are formed usually have a greater 

 resistance to injurious influences than do the vegetative forms 

 of the species which are capable of producing spiires. 





^^>. • 





Fig. _'7 — Showing sjior.' formation. 



Bacterial food requirements are quite variable. Some types 

 of bacteria recjuire preformed organic compounds and r.tliers 

 appear to have the power of synthesizing the simplest com- 

 pounds and available elements into new compounds upon which 

 thev subsist. Until recently it was supposed that synthesis was 

 confined to chlorophvllaceous plants \mt some species of bac- 

 teria are now known to posess the power of building complex 

 compounds from simple materials, e. g.. the nitrifying bacteria. 

 Parasitic bacteria and most saprophytic bacteria as a rule 

 require preformed organic compounds for their food. Some 



