CELL GROUPINGS 



55 



cocci, these indicate one-plane division only. Cocci show 

 their characteristic groupings only when grown in a liquid 

 medium, and such should always be used before deciding on 

 the plane of division. 



Fig. 46. — Staphylococcus group- 

 ing. The large flat masses are 

 staphylococcus grouping. Diplo- 

 coccus grouping, tetrads and short 

 streptococci are also evident. 



Fig. 47. — Sarcina grouping. 



As the above description shows, these terms which are 



. .;c(_:v ;.;,£; iKCtives describing the cell grouping, are quite 

 seuerally iiistsd as nouns. Thus the terms a diplocoecus, a 

 i.tJiKaia;, a streptococcus, etc., are common, meaning a bac- 

 terium of the cell form and cell grouping indicated. 



Cell Fobm. 



coccus — round or spherical. 



bacillus — rod-shaped or 

 cylindrical. 



spirillum — spiral-shaped . 



Cell Grouping. 



diplocoecus — ^in 2's. 



streptococcus — ^in chains. 



tetracoccus, tetrads — in 4's. 



staphylococcus — irregular flat masses. 



sarcina — regular, solid" packets, multiples 

 , of 8. 



/ diplobacillus — in 2's. 

 \ streptobaciUus — ^in chains. 

 / diplospirillum — in 2's, little used. 

 \ streptospirillum — in chains, little used. 



