THE HIGHER BACTERIA. 15 



have done, as a general term for the whole group. It is usual to call all the 

 rod-shaped varieties bacilli. And until the botanists themselves agree to 

 adopt a common standard of nomenclature, it is preferable, we think, to retain 

 the use of the older system throughout this work. 



3. Spirilla. These consist of cylindrical cells more or less 

 spiral or wavy. Of such there are two main types. In one 

 there is a long non-septate, usually slender, wavy or spiral thread 

 (e.g. spirillum of relapsing fever, Fig. I, No. 9). In the other type 

 the unit is a short curved rod (often referred to as of a " comma " 

 shape). When two or more of the latter occur, as they often do, 

 end to end with their curves alternating, then a wavy or spiral 

 thread results. An example of this is the cholera microbe (Fig. 

 i, No. 10). This latter type is of much more frequent occurrence, 

 and contains the more important species. Among the first group 

 motility is often not associated, as far as is known, with the pos- 

 session of flagella. The cells here apparently move by an undu- 

 lating or screw-like contraction of the protoplasm. Most of the 

 motile spirilla, however, possess flagella. Of the latter there 

 may be one or two, or a bunch containing as many as twenty, at 

 one or both poles. Division takes place as among the bacilli, and 

 in some species endogenous sporulation has been observed. 



Three terms are used in dividing this group, to which different authors 

 have given different meanings. These terms are spirillum, spirochaeta, vibrio. 

 Migula makes " vibrio " synonymous with " microspira," which he applies to 

 members of the group which possess only one or two polar flagella ; " spiril- 

 lum " he applies to similar species which have bunches of polar flagella, while 

 "spirochaeta" is reserved for the long unflagellated spiral cells. Hueppe 

 applies the term "spirochaeta" to forms without endospores, "vibrio" to 

 those with endospores in which during sporulation the organism changes its 

 form, and " spirillum *' to the latter when no change of form takes place in 

 sporulation. Flugge, another systematist, applies " spirochaeta " and " spiril- 

 lum " indiscriminately to any wavy or corkscrew form, and " vibrio " to forms 

 where the undulations are not so well marked. It is thus necessary, in de- 

 nominating such a bacterium by a specific name, to give the authority from 

 whom the name is taken. 



II. The Higher Bacteria. These show advance on the lower 

 in consisting of definite filaments branched or unbranched. In 

 most cases the filaments at more or less regular intervals are 

 cut by septa into short rod-shaped or curved elements. Such 

 elements are more or less interdependent on one another, and 

 special staining methods are often necessary to demonstrate the 



