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The Origin and Destiny of Cholesterol in the Animal Organism. 

 Part V. — On the Inhibitory Action of the Sera of Rabbits 

 fed on Diets containing V arying Amounts of Cholesterol on 

 the Hemolysis of Blood by Saponin. 



By Mary T. Fraser and J. A. Gardner, 



(Cornniunicated by Dr. A. D. Waller, F.R.S. Received April 3, — Eead 



May 6, 1909.) 



(From the Physiological Laboratory, University of London, South Kensington.) 



In an earlier paper* of this series it was shown that cholesterol is not 

 excreted in the feces of herbivorous animals, and that when rabbits are fed 

 on a diet free from phytosterol but containing measured quantities of 

 cholesterol, a portion of the latter substance is absorbed. The hypothesis 

 was put forward that cholesterol is a substance which is strictly conserved in 

 the animal economy ; that when the destruction of the red blood corpuscles 

 and possibly other cells takes place in the liver, their cholesterol is excreted 

 in the bile, and that the cholesterol of the bile is reabsorbed in the intestine 

 along with the bile salts, and finds its way into the blood stream to be used 

 in cell-anabolism. It was also suggested that any waste of cholesterol might 

 possibly be made up from that taken in with the food. In order to test this 

 view, comparative estimations were made of the total cholesterol content 

 of the blood of rabbits that had been respectively fed on bran which had 

 previously been thoroughly extracted with ether, and on the same extracted 

 bran with the addition of known amounts of cholesterol, care being taken 

 that the animals were otherwise identically treated and were kept in good 

 health. The results of the experiments showed that some, at any rate, of the 

 cholesterol absorbed found its way into the blood stream. It seemed to us 

 desirable to ascertain next whether the cholesterol was absorbed into the 

 blood stream as such or in the form of esters or in both states, and also 

 whether the phytosterol of vegetable food can be utilised for the formation 

 of cholesterol in the organism. Owing to the small percentage of these 

 substances in the blood, it did not seem probable that the chemical methods 

 hitherto available for their estimation were sufficiently accurate to give 

 reliable information unless in each experiment a larger number of animals 

 was taken than We could conveniently attend to. It seemed likely, however, 

 that a comparative study of the inhibitory effects of the sera of rabbits fed 



* "Origin and Destiny of Cholesterol," Part III, 'Eoy. Soc. Proc.,' B, vol. 81, 1909 

 p. 109. 



