512 Messrs. Ellis and Gardner. Origin and [Aug. 14. 



solution of bromine to the solution of the substance in ether ; this was filtered 

 off and reduced in glacial acetic acid solution with zinc dust. The product, 

 which should have been cholesterol, had it been present in any quantity, on 

 heating began to soften at 137° and was not completely melted until 142° C. 

 An examination of the crystals under the microscope showed that they con- 

 tained phytosterol. The soluble dibromide treated in a similar way gave a 

 substance melting at 138° — 140° C. A microscopic examination showed that 

 this was largely phytosterol. 



The residues, after the separation of the T3545 grammes of phytosterol, 

 were treated in pyridine solution with benzoyl chloride ; 0T196 gramme of 

 benzoate was obtained. This, after recrystallisation from alcohol, melted at 

 145° — 146° C.'to a clear liquid and on cooling showed colours, though not 

 very brilliantly. On carefully examining the crystals under the microscope, 

 they were found to consist of phytosterol benzoate and none of the typical 

 square plates of cholesterol benzoate could be seen. The conversion of 

 phytosterol into the benzoate by the pyridine method is by no means quanti- 

 tative, so that we do not know whether all was recovered from the residues. 

 Altogether 1*4487 grammes of phytosterol were recovered, including, of 

 course, cholesterol if present. All the phytosterol given in the food was, 

 therefore, excreted unchanged, but whether accompanied by cholesterol we 

 cannot say. There could not, however, have been much. 



X. Immediately after the conclusion of the last experiment the diet was 

 continued, but with the substitution of cholesterol for phytosterol. The 

 experiment lasted 12 days, cholesterol being given with the food on the first 

 eight days only. During the period the animal ate 620 grammes of germ 

 and 2 grammes of cholesterol : 138 grammes of dried faeces were collected 

 and the yield of unsaponifiable matter was 2*1775 grammes in the form of a 

 brown solid. After recrystallising twice from alcohol, 1*5455 grammes of 

 cholesterol, melting at 145° — 147° C, were obtained. This figure is rather 

 low owing to an accident, but the amount lost was under one-tenth of a 

 gramme. The residues on benzoylation yielded 0*4386 gramme of cholesterol 

 benzoate. The total cholesterol obtained was, therefore, 1*89 grammes, so 

 that the total amount excreted could not have been greater than the weight 

 of the cholesterol administered. 



Discussion of the Results. 



The conversion of cholesterol into coprosterol in the gut of the cat appears 

 to take place only in the case of meat diets, and then the change is not 

 necessarily complete. The two cats in Experiments I and II which yielded 

 only coprosterol had been previously fed for some time on sheep's brain. The 



