STABLE MANURES AND FECAL RESIDUES 21 



concentration of bacterial substance may, therefore, have been even 

 greater. 



It has been reported (441 ) that i ml. of the intestinal contents of cat- 

 tle contains 10 billion cells capable of development. By suitable methods 

 of cultivation, human feces were found (588) to contain 18 billion 

 bacteria per gram. Determination (542) of the number of bacteria in 

 stable manure gave 1 1.6 billion cells per gram of material by the plate 

 method, and, by the dilution method, 5 billion peptone-decomposers, 

 100 million urea-decomposers, and 2.5 million cellulose-decomposers. 

 About 100 billion bacteria may be produced daily in the human in- 

 testine. Human feces are made up, on an average, of 32,4 per cent bac- 

 terial cells amounting to 2,410 millions of bacteria per milligram of 

 moist material. Feces of healthy persons were shown (300) to contain 

 8.2 to 24.2 per cent bacterial cells j in those of persons suffering from 

 intestinal disturbances the percentages were 20.1 to 40.2. With the de- 

 velopment of the microscopic technique for counting bacteria, much 

 larger numbers of cells were shown to be present than could be deter- 

 mined by the plate method. 



The urine of healthy persons is sterile or very low in bacteria. Be- 

 cause of the ability of many bacteria to utilize the chemical constituents 

 of urine, rapid bacterial multiplication takes place in fresh urine, espe- 

 cially when mixed with animal feces and bedding (775). 



The microbiological population of animal excreta is characteristic. In 

 addition to the common fecal bacteria, it contains fungi, thermophilic 

 bacteria, and, in herbivorous animals, anaerobic cellulose-decomposing 

 bacteria (543). 



Various methods have been developed for permitting the prefer- 

 ential development of certain types of bacteria. Gram-negative bacteria 

 in the feces can be repressed by certain reagents (839) j gram-positive 

 bacteria can be repressed by the addition of antibiotic substances such as 

 actinomycin (Table 4). 



The bacterial population of fresh cow manure was found (796) to 

 consist of 47.5 per cent streptococci {Streftococcus -pyogenesy Sarcina sp., 

 and Micrococcus candkans) ,21,2 per cent coli-like colonies {Escherichia 

 coli,A. aero genes y and S. sefticemiae), and many dark colony-forming 

 types. Other groups represented were BacteroideSy Flavobacteriuniy 



