CONTENTS XI 



III. The Digestibility of Fats (continued) 



(2) Procedure of Deuel, Johnson et al 197 



(3) Methods for the Study of Digestibility of Lipids in Rats 199 



a. General Procedures 199 



b. Determination of Metabolic Lipid 201 



(4) Methods for the Study of the Digestibility of Lipids in Dogs 202 



(5) The Use of Inert Chemical Substances as Indices of Digestibility. . . 203 



a. Ferric Oxide as an Inert Material in the Determination of Digesti- 



bility 203 



b. Lignin as an Inert Material in the Determination of Digestibility 204 



c. Silica as an Inert Material in the Determination of Digestibility . . 204 



d. Chromic Oxide as an Inert Material in the Determination of Di- 



gestibility 205 



e. Indigestible Chromogenic Substances as Inert Materials in the 



Determination of Digestibility 206 



f. Comparison of Different Technics for the Determination of Di- 



gestibility 207 



(6) Determination of Fecal Lipids 207 



a. Methods Employing Dried Feces 207 



b. Methods Employing Wet Feces 210 



(7) Methods for the Determination of Inert Chemical Substances 211 



a. Lignin 211 



b. Chromic Oxide 212 



(8) Special Methods for the Calculation of Digestibility of Lipids 212 



a. General Formulas for the Calculation of Digestibility of Higher 



Alcohols, Hydrocarbons, or Waxes 213 



3. Digestibility Studies on Fats, Oils, and Fatty Acids 215 



(1) Studies on Human Subjects 215 



a. Digestibility of Vegetable and Animal Fats Melting Under 50°C. 215 



b. Digestibility of High-Melting Fats 218 



c. Digestibility of Oleomargarines 220 



(2) Studies on Animals Other Than Man 221 



a. Digestibility of Natural Fats 221 



b. Digestibility of Simple Triglycerides and Fatty Acids 225 



4. Normal Factors Altering the Digestibility of Fats 227 



(1) The Effect of Age 227 



(2) The Effect of Sex 228 



(3) The Effect of Species 228 



(4) The Effect of Melting Point 229 



(5) The Effect of Structural Configuration 230 



(6) The Effect of Polymerization 232 



(7) The Effect of Emulsifying Agents 235 



(8) The Effect of Foodstuffs Concomitantly Present with Ingested Fat. 235 



a. The Effect of Calcium and Magnesium Salts 235 



b. The Effect of Protein 239 



c. The Effect of Crude Fiber 239 



(9) Miscellaneous Factors 240 



