The use of straw as fodder is beset by the double difficulty that on the one hand its bulky character seriously limits the extent to which it can be consumed by the animal, whilst on the other hand its tough and fibrous nature entails such a heavy expenditure of energy to secure the high degree of comminution and further preparation essential for effective action of the digestive agents that only a comparatively small surplus of energy remains over to serve productive nutritional ends. Thus it was found by Kellner and Köhler in the case of oat straw that of the total energy contained in the straw only 35·8 per cent, was usefully digested, whilst only 12·9 per cent, could be applied after digestion to productive purposes. For wheat straw the corresponding proportions were 31·1 per cent, and 5·5 per cent, respectively. These may be contrasted with the proportions of 49 per cent, and 20·7 per cent, respectively found by the same observers for meadow hay; and the proportions of 74·9 per cent, and 45·9 per cent, respectively found by Armsby and Fries for maize meal.