334 AGRICULTUEAL AND INDTJSTEIAL BACTEEIOLOGY 



nature except in places or localities fouled by the excretions 

 of the body. It is very easily cultivated in the laboratory 

 and it is probable that under certain conditions in nature it 

 may multiply for a brief period of time outside the body. 

 This, however, does not commonly occur, at least not in vir- 

 gin soil or in unpolluted water. It is so abundant in feces 

 that it has come to be looked upon generally in England 

 and America as an indication of fecal contamination when 

 found in water. It is not because Bacterium coli itself is 

 pathogenic, but because it is an indicator of the presence of 



Fie. 66. — ^Bacterium coli. 



such fecal pollution that water containing it is generally 

 condemned for domestic use. 



Morphology. — The organism is a plump rod 0.4-0.7/i 

 X 2-4/4. When growing rapidly it may be coccuslike. It 

 rarely occurs in chains. Spores and capsules are not pro- 

 duced. It is actively motile, stains readily and is Gram- 

 negative. 



Cultural Characters. — The organism grows readily upon 

 most culture media. Gelatin is not liquefied. Bouillon is 

 clouded, sometimes with the formation of a pellicle. The 

 growth upon potato is moist and spreading, the potato 

 becoming darkened, sometimes almost black. Milk is coag- 

 ulated with the formation of lactic acid and gas; the curd 



