Aug. 15, 1921 
Bacteriology and Chemistry of Different Silages 
769 
METHOD OF PROCEDURE 
Two main sets of experiments were planned—first, field experiments; 
second, laboratory experiments. Several investigations were planned 
under each set. It was planned to make an analysis at the time of 
storage, every other day for a week, every three days for the next week, 
and then once every week until the silage was about a month old. There 
were times in making these analyses when it was necessary to deviate 
slightly from the original plans. 
SILOS 
The two silos used in storing the different kinds of field silage were of 
the monolithic concrete type with inside dimensions of 8 feet in diameter 
and 30 feet in height. The walls, 6 inches in thickness, were nonporous 
and the inside was made smooth with a coat of plaster. To afford a 
means of sampling, pieces of 2-inch water pipe 6 inches long were placed 
in the wall at the time the silos were constructed. These sample holes 
were located 3 to 5 feet apart all the way around the silos to a height of 
12 feet and were plugged. 
The samples used in all tests were obtained by making repeated bor¬ 
ings through these holes with a 2-inch auger. A new hole was used for 
obtaining material for each successive analysis. The auger was provided 
with an extension shaft 8 feet in length so as to penetrate to the center 
of the silo. 
The silos used for laboratory experiments consisted of quart milk bot¬ 
tles, stoppered with rubber stoppers wired in, and sealed with paraffin. 
One bottle of silage was used for each day's analysis. 
BACTERIOLOGICAL METHODS 
Samples of silage were collected from the concrete silos in sterile con¬ 
tainers and taken to the laboratory. In order to secure a representative 
sample the silage was passed through a sterile meat grinder. Twenty 
gm. of this silage were placed in 200 cc. of sterile physiological salt solu¬ 
tion. This was thoroughly shaken, and further dilutions were made. 
Total number of microorganisms. —In determining the total num¬ 
ber of bacteria, plain agar was used. No doubt a somewhat greater 
number of organisms could have been obtained with a carbohydrate 
medium, but the relative increase or decrease in the number would have 
been the same. 
Total acid producers. —Dextrose litmus broth and dextrose eresol 
purple broth were used. Dextrose litmus broth was prepared by using 
1 per cent dextrose broth to which litmus had been added. Cresol purple 
solution was made by dissolving 0.4 gm. of di-bromo-ortho-cresol- 
sulphonphthalein in a minimum amount of alcohol and making up to 1 
liter with water. Forty cc. of this were added to 1 liter of dextrose 
broth. The broths were inoculated with different dilutions of the silage 
