122 MANUAL OF BACTERIOLOGY. 



be demonstrated when the bacteria are obtained from the 

 fluids derived from an animal's body than when they have 

 been grown artificially in culture-media. A zoogloea is a 

 large mass of bacteria in a resting condition held together 



by a mucilaginous substance. The 



F IG. 43. 



composition of bacteria varies con- 



<*?> I) siderably with different species. 



The basis a PP ears to be P roteid 

 substance. 



T* 16 multiplication of bacteria 



Bacteria with Capsules. takes P lace in almost all CaSCS by 



transverse fission. The formation 



of tetrads or sarcinae from micrococci depends upon fission in 

 two or three planes. Repeated fissions of micrococci in one 

 plane result in the formation of streptococci. Micrococci 

 that have recently divided are likely to be somewhat flat- 

 tened. Multiplication under favorable circumstances may 

 take place at a phenomenally rapid rate. Bacilli have been 

 observed to divide in twenty minutes. If division takes 

 place once in an hour, the progeny of one organism at the 

 end of twenty- four hours will be 16,777,216, i. e., (2 X i) 24 - 

 The ordinary form of reproduction by fission is called 

 vegetative, and bacteria that are multiplying in this man- 

 ner are often spoken of as being in the vegetative condi- 

 tion. 



FIG. 44. 



Or 



); 



Bacteria with Spores. 



Spores. Under certain circumstances the reproduction 

 of bacteria takes place by means of bodies called spores. 



