§ II.] Cell-unions, Cell-groupings. 1 1 



a. The cells arranged in rows in the direction of the succes- 

 sive divisions. From their thread-like form these cell-rows 

 (Fig. 2, &c.) are termed filaments in accordance with the 

 traditional terminology; a strange confusion of ideas led to 

 their being also called pseudo-filaments, objects which look like, 

 but are not real, filaments. 



It is obvious after the foregoing remarks, first, that these 

 filaments must be of different shape according as the individual 

 cells are round or of some other form ; secondly, that the 

 length of the filaments, measured by the number of cells, may 

 be very various. It may be said specially of the rod-like and 

 spiral forms, that the cells usually remain united into short 

 rows in such a manner that the rod or spiral is actually 

 composed of more than one cell, and then after a definite 

 increase of the entire length and of the number of the segment- 

 cells is divided into two at the oldest points of division. The 

 ■words Leptothrix, Mycothrix, and others designate the longer 

 filamentous forms. 



b. Cells united together and arranged genetically in a simple 

 surface, or as a body of three dimensions, are of less frequent 

 occurrence, as has been already said ; Zopf s Bacterium meris- 

 mopoedioides may be given as an example of the former kind, 

 of the latter the cube-shaped cell-packets of Sarcina ventriculi 

 (see Fig. 14). 



By the side of these phenomena of genetic union and variou.sly 

 combined with them appears a series of groupings, as they may 

 be briefly termed, which owe their character to a great extent to 

 the mass, cohesion, and other specific qualities of the gelatinous 

 membranes as these are formed, and next and in combination 

 with these, to their own very various specific peculiarities, which 

 cannot, as a rule, be shortly defined ; some explanation of the 

 latter, though unfortunately only an imperfect one, will be given 

 further on when we are considering vital processes. The nature 

 also, and especially the state of aggregation of the substratum, 

 may in certain circumstances have an influence on the grouping. 



