THE BIOLOGY OF BACTERIA II 



merismopedia. In both these conditions it frequently hap- 

 pens that the contiguous sides of the elements of packets 

 become faceted or straightened against each other. It may 

 happen, too, particularly in the sarcince, that segmentation is 

 not complete, and that the elements are larger than in any 

 other class of cocci. They stain very readily. Nearly all 

 the cocci are non-motile, though Brownian movement may 

 readily be observed. 



2. The Bacilli. These consist of rods, having parallel 

 sides and being longer than they are broad. They differ in 

 every other respect according to species, but these two 

 characteristics remain to distinguish them. Many of them 

 are motile, others not. The ends or poles of a bacillus may 

 be pointed, round, or almost exactly square and blocked. 

 They all, or nearly all, possess a capsule. Individuals of the 

 same species may differ greatly, according to whether they 

 have been naturally or artificially grown, and pleomorphic 

 forms are abundant. 



3. The Spirilla. This wavy thread group is divisible into 

 a number of different forms, to which authorities have given 

 special names. It is sufficient, however, to state that the two 

 common forms are the non-septate spiral thread (like the 

 Spirillum Obermeier of relapsing fever), which takes no other 

 form but a lengthened spirillum ; and the spirillum which 

 breaks up into elements or units, each of which appears 

 comma-shaped (like the cholera bacillus). The degree of 

 curvature in the spirilla, of course, varies. They are the 

 least important of the lower bacteria. 



The Higher Bacteria group includes more highly organised 

 members of the Schizomycetes. They possess filaments, 

 which may be branched, and almost always have septa and 

 a sheath. Perhaps the most marked difference from the 

 lower bacteria is in their reproduction. In the higher bac- 

 teria we have what is in fact a flower terminal fructifica- 

 tion by conidia. In this group of vegetables we have the 



