1. 1) S. Ishikawa and Y. Furuichi: Reliability of polyethyleneglycol as anindicator for digestion studies with swine. Part II. Variation of polyethyleneglycol evacuation and estimate of digestibility. Agricult. Biol. Chemi., 32, 1086-1092 (1968).
2. 2) S. Ishikawa and K. Sugimura: Movement of polyvinylalcoholthrough the digestive tract as a digestion indicator with swine. Agricult. Biol. Chemi., 37, 203-206 (1973).
3. 3) E. J. Castle and M. E. Castle: The rate of passage of food throughthe alimentary tract of pigs. J. Agricult. Sci., 47, 196-203 (1956).
4. 4) S. lshikawa: Chromic oxide indicator method for digestibility stu-dies with swine (IX) Rate passage of nutrients through the digestivetract. Bull. Fac. Agricult, Mie Univ., 23, 59-74 (1961).
5. 5) P. Calow and C. R. Fletcher: A new radiotracer technique involving 14C and 51Cr, for estimating the assimilation efficiencies of aquatic, primary consumers. Oecologia, 9, 155-170 (1972).