18 



MICROBIOLOGY 



shaped (bacterium and bacillus), and the spiral (spirillum). 

 Although these forms vary considerably it is ordinarily not 

 difficult to determine to which type a given organism be- 

 longs. These forms, within well defined limits, are constant 

 when under conditions favorable to growth. The micro- 



'/ 



1 2 - : 



Fig. 4. Streptococci (micrococci in chains). 1, long slender 

 chains;. 2, shorter chains in which the segments appear in pairs. 





-I- -Z- -3- 4- -5- -6- -7- 



Fig. 5. Bacilli. 1, different shaped rods; 2, showing spores; 3, 

 capsules; 4, flagella; 5 and 6, granules; 7, involution forms. 



-3- 



-I- -2- 



Fig. 6. Bacterium. 1, different forms; 2, spores; 3, square at 

 ends; 4, united in short chains. 



<:,\ * V" ftft 



e s 



Fig. 7. Spirilla. The figures show different varieties of spiral 



forms. 



cocci produce micrococci; bacilli produce bacilli; and spirilla 

 produce spirilla. Although these types are constant, there 

 'is found on examining cultures of any of them while in the 



