220 PHARMACEUTICAL BOTANY 



hold eight billion of them the student commences his study of 

 bacterial growths in colonies or cultures, each kind possessing 

 characteristics by which they may be distinguished and differentiated. 

 The individuals in the colony, depending upon the kind of bac- 

 teria under examination, may be globular, rod-shaped, or spiral. 

 Bacteria are classed according to form into the following families 

 and genera. 



V 



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 O 4* 



FIG. 1 06. Types of micrococci. (After Williams.) 



Family I. Coccaceae. Cells in their free condition globular, be- 

 coming but slightly elongated before division. Cell-division in one, 

 two or three directions of space. 



A. Cells without Flagella. 



1. Division only in one direction of space forming an aggregation 

 resembling a chain of beads Streptococcus. 



2. Division in two directions of space forming an aggregation 

 resembling a cluster of grapes Staphylococcus. 



FIG. 107. Types of bacilli. (After Williams.) 



3. Division in three directions of space forming a package-shaped 

 or cubical aggregation Sarcina. 

 B. Cells with Flagella. 



1. Division in two directions of space Plajiococcus. 



2. Division in three directions of space Planosarcina. 



Family II. Bacteriaceae. Cells longer than broad, generally two 

 to six times, straight or only with an angular bend, never curved or 

 spiral, division only at right angles to axis or rod; with or without 

 flagella and endospores. 



i. Flagella and endospores absent Bacterium. 



