GENERAL REQUIREMENTS. 49 



layer of silage, the fermentation process will be more far- 

 reaching than is usually the case in the lower layers of 

 the silo. Putrifactive bacteria will then continue the 

 work of the acid-bacteria, and the result will be rotten 

 gilage. If no further supply of air is at hand, except what 

 remains in the interstices between the siloed fodder, the 

 bacteria will gradually die out, or only such forms will 

 survive as are able to grow in the absence of air. 



Another view of the cause of the changes occurring 

 in siloed fodder has been put forward lately, viz., that 

 these are due not to bacteria, but to "intramolecular res- 

 piration" in the plant tissue, that is due to a natural dying- 

 off of the life substance of the plant cells. From a practical 

 point of view it does not make any difference whether the 

 one or the other explanation is correct. The facts are 

 with us, that if much air is admitted into the silo, through 

 cracks in the wall or through loose packing of the siloed 

 mass, considerable losses of food substances will take 

 place, first, because the processes of decomposition are 

 then allowed to go beyond the point necessary to bring 

 about the changes by which the silage differs from green 

 fodder, and, second, because the decomposition will cause 

 more or less of the fodder to spoil or mold. 



2. The silo must be deep. Depth is essential in build- 

 ing a silo, so as to have the siloed fodder under consider- 

 able pressure, which will cause it to pack well and leave 

 as little air as possible in the interstices between the cut 

 fodder, thus reducing the losses of food materials to a 

 minimum. The early silos built in this country or abroad 

 were at fault in this respect; they were shallow struc- 

 tures, not over 12-15 ft. perhaps, and were longer than they 

 were deep. Experience showed that it was necessary to 

 weight heavily the siloed fodder placed in these silos, in 

 order to avoid getting a large amount of moldy silage. 

 In our modern silos no weighting is necessary, since the 

 material placed in the silo is sufficiently heavy from the 

 great depth of it to largely exclude the air in the siloed 

 fodder and thus secure a good quality of silage. In case 

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