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The Origin and Destiny of Cholesterol in the Anmal Organism. 
Part II].—The Excretion of Cholesterol by the Dog. 
By Cuartes Dorks, Lindley Student of the University of London, and 
J. A. GARDNER, Lecturer on Physiological Chemistry, University of 
London. 
(Communicated by Dr. A. D. Waller, F.R.S. Received February 10,— 
Read March 12, 1908.) . 
(From the Physiological Laboratory, University of London.) 
In a former paper* we showed that the so-called hippocoprosterol, which 
was considered by its discoverersf to be a reduced cholesterol, and the form 
in which the cholesterol of the bile of the horse is excreted in the feces, is 
contained in the solid excreta of all grass-fed herbivorous animals, and that 
it is not a product of the animal metabolism, but a constituent of the grass 
taken as food and passed unchanged. We also showed that cholesterol is not 
found in the feces of these animals. It therefore seemed to us desirable to 
extend the investigation to carnivora, and to ascertain, if possible, whether the 
cholesterol often found in their excreta is derived from the organism or from 
the food, and whether, under any circumstances, it is found in modified form 
as in the human subject. 
Of the various animals the dog appeared to be the most suitable for initial 
experiments, as it is easily trained and will thrive not only on meat but on 
vegetable diets. The animal selected for experiment was an Irish terrier 
bitch, between four and five years of age, and weighing 11°8 kilogrammes. It 
was quiet and used to a sedentary life. Preliminary experiments, using 
a mixed diet, showed that the quantity of cholesterol excreted per day was 
exceedingly small, much too small for even approximate estimation. We 
therefore decided to keep the animal under observation for the greater part 
of a year, and to feed it on particular diets for many consecutive days, 
varying from 14 to 30, according to circumstances. We did not think it 
necessary at this stage of the enquiry to make any determinations on the 
nitrogen metabolism during the experiments, but we took great care to keep 
the animal in good health during the whole time, by regular exercise, periods 
of rest, etc. During a part of the time the dog was kept at Messrs. Ridler 
and Hobday’s establishment, and we take this opportunity of expressing our 
* ‘Roy. Soc. Proc.,’ this volume, p. 212. 
t+ Bondzynski and Humnicki, ‘ Zeit. Physiol. Chemie,’ vol. 22, p. 396. 
