14 GENERAL MORPHOLOGY AND BIOLOGY 



the cocci have endogenous spores been certainly observed. The 

 species of the streptococci and staphylococci differentiated 

 number several hundreds. Usually included in this group are 

 coccus-like organisms which divide in three axes at right angles 

 to one another. These are usually referred to as sarcince. If 

 the cells are lying single they are round, but usually they are 

 seen in cubes of eight with the sides which are in contact 

 slightly flattened. Large numbers of such cubes may be lying 

 together. The sarcinse are, as a rule, rather larger than the 

 other members of the group. Most of the cocci are non-motile, 

 but a few motile species possessing flagella have been described. 



2. Bacilli. These consist of long or short cylindrical cells, 

 with rounded or sharply rectangular ends, usually not more than 

 1 [A broad, but varying very greatly in length. They may be 

 motile or non-motile. Where flagella occur, these may be 

 distributed all round the organism, or only at one or both of 

 the poles (pseudomonas). Several species are provided with 

 sharply-marked capsules (b. pneumonias). In many species 

 endogenous sporulation occurs. The spores may be central or 

 terminal, round, oval, or spindle-shaped. 



Great confusion in nomenclature has arisen in this group in con- 

 sequence of the different artificial meanings assigned to the essentially 

 synonymous terms bacterium and bacillus. Migula, for instance, applies 

 the former term to non-motile species, the latter to the motile. Hueppe, 

 on the other hand, calls those in which endogenous sporulation does 

 not occur, bacteria, and those where it does, bacilli. In the ordinary 

 terminology of systematic bacteriology the word bacterium has been 

 almost dropped, and is reserved, as we have done, as a general term for 

 the whole group. It is usual to call all the rod-shaped varieties bacilli. 



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 

 (Fig. 1, 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. 1, 

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

 Among the first group motility is often not associated, as far 

 as is known, with the possession of flagella. The cells here 

 apparently move by an undulating 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 



