CLASSIFICATION OF BACTERIA 17 



but in the same plane, so that lamellae or plates 

 are formed. 



Genus 4. SAKCINA. -Division in three directions at 

 right angles to one another and in two planes, eo 

 that cubical masses are formed. 



Genus 5. Ascococcus. Cocci which develop in a 



gelatinous matrix. 

 Family II. BACTERIACE^E. Rods, straight or curved, at 



some period of the life-history, though coccoid and 



other forms may occur. 



Genus 1. BACTERIUM. Straight rods ; endospore 

 formation does not occur. 



Genus 2. BACILLUS. Straight rods ; endospore 

 formation occurs. 



Genus 3. LEUCONOSTOC. Cocci and rods ; arthro- 

 spore formation occurs in the coccoid forms. 



Genus 4. CLOSTRLDIUM. The same as bacillus, but 

 the spore-bearing rods are enlarged and club- 

 shaped. 



Genus 5. SPIRILLUM. Spiral rods ; spore forma- 

 tion does not occur. 



Genus 6. VIBRIO. Spiral rods ; spore formation 



occurs . 

 Family III. LEPTOTRICHE^J. These are unbranching 



thread forms. 

 Family IV. CLADOTRICHE^:. These are thread forms 



showing true but not dichotomous branching. 



There are many features in this classification which 

 are of practical value. The distinction made between a 

 bacterium and a bacillus, for example, is convenient. 

 Formerly a short rod was termed a bacterium, and a long 

 rod a bacillus, but such a division is an arbitrary one, and 

 at one stage of its life-history an organism might be a bac- 

 terium and at another a bacillus. The term " bacterium " 



2, 



