208 Agricultural Bacteriology. 



Digestion of cellulose. Coarse fodder, such as hay r 

 straw, or corn fodder contains a large proportion of crude 

 fiber or cellulose. It is known that different kinds of 

 animals can digest this class of substances to a varying 

 extent. In the different digestive juices of the body have 

 been found enzymes that can attack carbohydrates, fats 

 and proteins. None have been discovered that have any 

 action on cellulose. There are in the feces of animals, 

 bacteria that can digest the cellulose, changing it to com- 

 pounds that can be used by the animal. It is asserted 

 that ruminating animals can digest 75 per cent of the 

 cellulose in their food, and the horse 50 per cent. Dogs 

 and the strictly carnivorous animals cannot utilize this 

 material at all. In the case of the ruminating animals 

 the food remains in the body for a long time, as for in- 

 stance, in the cow for six or seven days, and with sheep 

 possibly a still longer time. There is thus opportunity 

 for extended bacterial action in such a favorable environ- 

 ment. In man the food passes through the body in a 

 much shorter time, and there is not the opportunity for 

 the bacteria to attack the cellulose. 



It is very probable that the bacteria of the intestinal 

 tract are necessary to the well-being of all kinds of ani- 

 mals. At the time of birth, the intestines are free from 

 bacteria but within a short time, less than a day, the bac- 

 teria have invaded the entire tract. Definite kinds 'of 

 bacteria are found to occur. When these are replaced 

 by other forms, the animal is quite likely to suffer. 



Composition of barnyard manure. Manure is made 

 up of the solid and liquid excreta of the different kinds 

 of animals kept on the farm and of the litter used in the 

 stables. It thus contains all of the compounds found in 

 the plant, and will undergo, in the main', the same set of 



