STRUCTURE AND DEVELOPMENT OF BACTERIA 23 



forming chains and bunches, as streptococci and staphylococci. 

 Long filaments are also formed. 



Zooglea. When this gelatinous membrane is very thick, 

 irregular masses of bacteria will be formed, the whole growth 

 being in one jelly-like lump. This is termed a zooglea (f o>oj>, 

 animal, 7X0165, glue). 



Locomotion. Many bacteria possess the faculty of self- 

 movement, carrying themselves in all manner of ways across 

 the microscopic field some very quickly, others leisurely. 



Vibratory Movements. Some bacteria vibrate in them- 

 selves, appearing to move, but they do not change their 



Fig. 2. Types of flagella: a, Vibrio choleras, one flagellum at the end 

 monotrichia type; b, Bacterium syncyaneum, tuft of flagella at the 

 end, rarely at the side lophotrichia type; c, Bacterium vulgare, flagella 

 arranged all about peritrichia type (Lehmann and Neumann). 



place; these movements are denoted as molecular or " Brown- 

 ian," and are due to purely physical causes, such as may be 

 obtained by suspending fine grains of carmin in water. 



Flagella. Little threads or lashes are found attached to 

 many of the motile bacteria, either at the poles or along the 

 sides sometimes only one, and on some several, forming a 

 tuft. 



These flagella are in constant motion, and can probably be 

 considered as the organs of locomotion; they have not been 

 discovered upon all the motile bacteria, owing, no doubt, to 

 our imperfect methods of observation. They can be stained 

 and have been photographed. (See Fig. 2.) Flagella serve 



