1910.] Destiny of Cholesterol in the Animal Organism. 567 



separated, but was not weighed. The filtrate from this precipitate, which 

 should have contained any phytosterol which might have been present, 

 was boiled for two hours with 5 c.c. of glacial acetic acid and ^ gramme of 

 zinc dust to reduce the phytosterol dibromide to phytosterol. The liquid 

 was filtered from the excess of zinc and poured into water, when a small 

 amount of solid matter separated. This was taken up in ether, and the 

 ethereal solution, after shaking with dilute carbonate of soda to get rid of 

 acetic acid, was dried and evaporated. A small quantity of oily crystalline 

 substance was left. This was boiled for some time with acetic anhydride 

 to convert it into the acetate, and then poured into water. The acetate 

 which separated was crystallised from 95-per-cent. alcohol, and the crystals 

 under the microscope appeared to have the form of large thin plates. These 

 were compared with slides of cholesterol acetate and phytosterol acetate, and 

 appeared to resemble the former more closely than the latter. After 

 crystallising three times from alcohol the crystals melted sharply at 101° C. 

 Cholesterol acetate melts at 114° C, and phytosterol acetate at 127° C. 

 The quantity of material was much too small for any attempt at further 

 purification. The minute quantity of material remaining, along with the 

 residue obtained by evaporating mother liquors, was saponified, and the crude 

 product dissolved in pyridine and treated with benzoyl chloride. On 

 pouring into water a small quantity of solid matter separated. This was 

 mixed with some oily matter, and owing to its small amount was difficult to 

 purify. The crystals which separated from alcohol appeared under the 

 microscope to have the form of square plates similar to those of cholesterol 

 benzoate. There was not enough to determine the melting point. 



The crude sterol from the blood therefore consisted almost entirely of 

 cholesterol, and contained no detectable quantity of phytosterol. Had the 

 increased sterol content of the blood of bran-fed rabbits compared with the 

 blood of animals fed on extracted bran been due to absorbed phytosterol, we 

 think we could not have failed to obtain some definite evidence of its 

 presence by the above method. 



Conchisions. 



(1) The digitonin method for the estimation of cholesterol is very accurate, 

 and is capable of yielding reliable results even when only relatively small 

 quantities of material are available. 



(2) When cholesterol is given with the food of rabbits, some is absorbed 

 and finds its way into the blood streai^ An increase of both free cholesterol 

 and cholesterol esters takes place. 



(3) When animals are fed ou phytosterol, this substance is in part absorbed, 



