1910.] Destiny of Cholesterol in the Animal Organism. 563 



V, Experiments on the Cholesterol and Cholesterol Ester Content of the Blood 

 of Rahhits Fed on Diets containing Varying Amounts of Cholesterol. — The 

 methods of feeding the animals under experiment were similar to those 

 described in our former paper.* Large healthy rabbits were selected, as 

 nearly the same weight as possible, and great care was taken to keep them 

 in good health, and, as far as possible, under the same conditions. The 

 blood of these rabbits was taken and divided into two portions, as nearly 

 equal as possible, which were weighed and mixed with sand and plaster of 

 Paris, as already mentioned. The mixtures, when dry, were extracted in a 

 Soxhlet apparatus with ether, the ether evaporated to dryness, and the 

 residues weighed. The free cholesterol was estimated by direct precipitation 

 with digitonin in the case of the residue from one portion, and the total 

 cholesterol estimated by saponifying the ethereal extract from the other 

 portion and estimating the cholesterol in the residue obtained after 

 saponification. The cholesterol present in the form of ester was then 

 obtained by difference. 



In the first set of experiments four rabbits were fed, for comparison, two- 

 on extracted bran alone and two on extracted bran plus a measured 

 quantity of cholesterol. These rabbits were kept under the same conditions, 

 and to be comparable, as far as possible, were killed within about ten 

 minutes of each other. 



Rahhit 1. — Fed for five days on extracted bran plus measured amounts of 

 cholesterol, ^ gramme first two days, \ gramme last three days ; total amount 

 2 grammes. Weight of rabbit = 27 kilogrammes, constant during whole 

 experiment. Total weight of blood = 62-461 grammes. Rabbit killed 

 4 hours 35 minutes after administration of cholesterol. 



(«) By direct precipitation 25-263 grammes of blood gave 0-0562 gramme 

 ether extract, which gave 0-0511 gramme compound = 0-0124 gramme 

 cholesterol, a percentage of 0-0492 free cholesterol in the blood ; and 



{h) By saponification 37-198 grammes of blood gave 0-0822 gramme ether 

 extract, which gave 0'1342 gramme compound = 0-0326 gramme cholesterol, a 

 percentage of 0-0877 total cholesterol in the blood and 0-0385 per cent, of 

 ester cholesterol by difference. 



Rahhit 2. — Fed for five days on extracted bran plus cholesterol, I gramme 

 for first two days, then ^ gramme for last three days. Total weight of 

 cholesterol = 2 grammes. Killed 4 hours 50 minutes after administration 

 of cholesterol. Weights of rabbit taken periodically during experiment 

 = 2-9, 2-9, 3 kilogrammes. Total weight of blood = 96-011 grammes. 



(a) By direct precipitation 51-451 grammes of blood yielded 0-1156 gramme 

 * ' Eoy. Soc. Proc.,' 1909, B, vol. 81, p. 231. 

 VOL. LXXXII. — B. 2 U 



