1 6 BACTERIOLOGY. 



real filamentous species, and whether the in- 

 dividual elements in the association are large 

 or small. Early observers indeed, especially 

 Ehrenberg and Naegeli, fell into the error of 

 assuming that there is really only one funda- 

 mental form, the coccus, out of which by vari- 

 ous combinations all the other forms can be 

 derived. 



B. Growth can occur also in two dimen- 

 sions so that flat sheets of cells are formed. 

 If growth takes place by cross-division, then 

 groups of four cells, tetrads or tablet-forms, 

 result. If division is longitudinal in rods 

 which remain in contact at one point, a radiat- 

 ing structure is produced (Fig. 6). 



C. By division of the cells in all three di- 

 mensions, cubical masses or packets like bales 

 of merchandise are formed. These are the so- 

 called Sarcincz (Fig. 7). 



D. Finally there may arise wholly irregu- 

 lar groups or heaps which have a spherical, 

 lobed or botryoidal appearance. To such ir- 

 regular cell-clusters names like Ascococcus, 

 Staphylococcus, Clathrocystis, Zobglcea rami- 



gera, etc., have been applied (Fig. 8). Indi- 

 vidual cells may be grouped and united in dif- 

 ferent ways in one and the same species under 

 varying conditions of life. 



Among the rod-shaped organisms especially 



