THE TYPHOCOLON BACILLI 159 



arranged all about the cell wall. It grows with ease artificially, 

 best in the presence of oxygen, but also in its absence. Devel- 

 opment will occur at any temperature from 10 to 43 C. or 

 50 to 108 F. It produces no spores. No color or pigment 

 is developed when cultivated in the laboratory. It possesses 

 the power of coagulating milk and of acid fermentation, with 

 the production of gas, in most of the carbohydrates (sugars 

 and starches) used for the differentiation of bacteria. It 

 does not produce ferments capable of liquefying gelatin or 

 the milk curd. It does, however, break up simpler substances 

 and forms indol, a putrefaction product. 



The colon bacillus is killed at 60 C. or 140 F. in ten 

 minutes. It resists freezing for a long time, perhaps several 

 months. Drying usually kills in one day, but certain indi- 

 viduals may remain viable for many days or weeks. It is 

 killed by carbolic acid, 1 to 1000, in twenty minutes, or 5 

 per cent, in two minutes in watery suspension. About the 

 same times hold for bichloride of mercury, 1 to 4000 and 1 

 to 1000. To weak acids it is resistant, as is shown by its 

 passage in food through the hydrochloric acid of the stomach. 

 This is also true of the typhoid bacillus. It will multiply in 

 feebly acid or alkaline solutions. Direct sunlight kills almost 

 at once, while diffuse light is withstood for a long time. 



The colon bacillus is found in the intestines of man and 

 animals in health or disease. It is expelled with the feces 

 and therefore gets into water-courses. The bacilli may be 

 found in the superficial layers of the earth. Examination 

 of water for public health purposes aims at its discovery as 

 an indication of sewage pollution. Its presence in milk may 

 be accounted for by contamination of milk in cans washed 

 with polluted water. It should not be forgotten that despite 

 the greatest personal care, colon bacilli are widely distributed 

 on everything that comes in contact with man and animals. 

 The newborn baby's intestine is free of them, but does not 

 long remain so, as the organisms find their way in with food 

 from the hands of attendants, or possibly through the anus 



