68 ATLAS OF BACTERIOLOGY. 



Spherical series (o), up to eight spheres, with the 

 separation merely indicated; torula shape (/>). 



Spherical threads (q), or, if curved, rosary shape 

 (s) ; with the separation merely indicated ; filaments 

 free from torula (r) . 



Grape shape (t). Double rods (u). Filaments of 

 links (v). 



Tetrads (w), a combination upon one plane of four, 

 eight, sixteen, or more cells. 



Dice shape (x), a combination of eight, thirty -two, 

 etc., cells. 



The formation of branches (dichotomy), i.e., the 

 production of a lateral sprout in bacteria, was un- 

 known until recently, and is at all events rare. It has 

 been demonstrated positively in the tubercle, diphthe- 

 ria, and glanders bacilli (vide Plate 48, Fig. VIII.), 

 so that for the present these varieties occupy a posi- 

 tion between the bacteriaceae proper and the hy phomy- 

 cetes or filamentous fungi. 



A different interpretation attaches to pseudodichot- 

 omy, which, according to Babes (Z. EL, XX., 412), 

 occurs not very rarely in the most typical bacteria. 

 Either the lower link of a filament grows past the 

 upper one and to one side, or, in a coccus series, a 

 division of a coccus parallel to the direction of the 

 filament suddenly initiates the beginning of a sec- 

 ond filament. 



Much has been written recently concerning the 

 structure of the bacterium cell. We must confine our- 

 selves to a mere abstract. 



According to Biitschli ("Ueber den Bau der Bak- 

 terien," etc., Heidelberg, Winter, 1890) (Fig. 3), the 

 bacterium cell consists of a membrane; a layer of 



