CHAPTER X. MORPHOLOGY OF THE BACTERIA. 459 



terminology adopted in the case of the Scytonemeae is also applied to this form of 

 branching in the Schizomycetes, which has therefore been designated by the really in- 

 correct or at least unnecessary name of 'false branching (pseudo-ramification). 



In some of the larger forms of this group, Crenothrix for example, Cladothrix, 

 and species of Beggiatoa, the filaments attach themselves by one extremity to fixed 

 bodies, while the other extremity stretches free into the surrounding fluid; here 

 therefore there is a distinction between base and apex, and this is accompanied by 

 certain corresponding phenomena of growth, such as the direction of the branches 



and some others. 



^ 



The formation of filaments occurs in those Schizomycetes in which growth and 

 divisions advance only or chiefly in one, and that the longitudinal direction. If these 

 take place alternately in two or three directions while the genetic connection is 

 maintained, then 



3. Groups of cells are produced forming flat surfaces or masses. The 

 dice-shaped pockets of Sarcina ventriculi are the best-known examples of this kind. 

 Figs. i7o/> x and 175 a will give an idea of their appearance. 



4. The isolated and connected forms of each of the kinds described above may 

 again be united by coherent mucilage into larger gelatinous masses, which are known 

 by the older and more general name of Palmella, or by the more recent term of 

 Zoogloea. These masses form gelatinous layers or pellicles according to the 

 species or culture-form, and cover the surface of the solid or fluid substratum ; or 

 if suspended in a fluid they form lumpy bodies of very various shapes and are often 

 lobed and branched. The gelatinous cell-membranes in these masses are either 

 fused together into a homogeneous structure, or show a stratification which varies 

 in the different isolated cells or aggregates of cells. In the larger and more firmly 

 united masses the cells, whether isolated or connected together, have not the power 

 of locomotion which many of them, as we have seen, possess in the free state. \ 



All these varieties of shape and connection are merely growth-forms like those 

 designated Filamentous Fungi, Sprouting Fungi, Compound Fungus-body, &c. 

 (see section I). But the Bacteria were at first distinguished into species 

 and genera^ according to these forms of growth, and on the too hasty assump- 

 tion that the forms produced from them were always like the parents, and 

 since the year 1872 these distinctions have been precisely defined by Cohn. But 

 it is obvious from what has now been stated that we are dealing in the present case 

 with form-species and form-genera only, using these words in the sense assigned 

 to them on page 120; the names Micrococcus, Bacillus, Spirillum, Spirochaete, 

 Vibrio, Leptothrix, Zoogloea and others, applied above to the Schizomycetes, were 

 in this sense used originally as names of genera and not as designations of forms 

 of growth. The relations of these form-genera to the natural genera, that is to the 

 genera founded on the entire course of development, will be considered presently. 



SECTION CXXX. The forms comprised under the name of Bacteria or Schizo- 

 mycetes may be distributed, in accordance with the course of their development 

 and with the facts as at present known to us, into two groups, and such is to some 

 extent the course adopted by Van Tieghem in his new text-book. The first group 

 will contain the species which have their spores formed endogenously, the Endo- 



