216 FARMYARD MANURE 



farm animals, together with the spores of Bs. enteritidis 

 sporogenes, the latter being especially abundant in fresh 

 pig dung. Heinick showed that the excreta from pigs 

 often contains Bact. lactis aerogenes, as well as B. coli, 

 and large numbers of the former organism have been 

 found in the intestinal canal and faeces of other animals 

 also. 



The bacteria mentioned may be considered natural 

 inhabitants of the digestive tract : others are introduced 

 in the food, and under certain circumstances may live 

 and increase in number within the animal, and be found 

 in the dung. A number of species also gain access to 

 the manure while it is in the stable and farmyard, and 

 multiply rapidly in it, the mixture of liquid and solid 

 excreta proving an excellent nutrient medium for them. 

 Some of the kinds are introduced in the litter and in the 

 fodder ; others are conveyed by the dust in the air and 

 the water used about the premises. 



Sewerin isolated from horse dung thirty-two species 

 or varieties, the majority of which in manure one month 

 old were rod-shaped organisms : cocci were compara- 

 tively uncommon until the manure had been stored three 

 months. In an old sample of stable manure Lohnis and 

 Kunze found forms of Proteus and the uro-bacteria most 

 abundant with large numbers of Bact. fluorescens (liquefy- 

 ing and non-liquefying forms) as well as Bact. putidum t 

 Bs. mesentericus, Bs. subtilis, and M. candicans : many 

 denitrifiers were isolated also. 



3. While many of the chemical changes which take 

 place in the dung heap are imperfectly understood, and 

 will require much research before they are completely 

 elucidated, some of the fermentations which occur 

 have been extensively investigated and their nature 



