In the preceding paper, attention is drawn to the fact that wide differences occur between individual animals in their capacity for converting food into fat. It is shown, for instance, that an individual ox on a fattening diet may increase in live weight as much as 3 lb. a day or as little as 1 lb. a day. The former would give out 17,000 Cals., and the latter 22,000 Cals. per day, a difference in heat evolution of about 25 per cent.