120 Messrs. Dor6e and Gardner. Origin and [Dec. 18, 



The standard of comparison employed by him was the cholesterol content 

 of the blood of a starving rabbit, which again is an abnormal case, since con- 

 ceivably some cholesterol might disappear from the blood during starvation, 

 and if this is so it is probably a variable standard, as different animals would 

 vary in the rate at which the cholesterol was removed from their blood. 

 Again, the quantities of cholesterol isolated and weighed were extremely 

 small, and were admittedly not pure. No melting points or other constants 

 were given, and we are consequently left uncertain as to whether the matter 

 weighed was cholesterol in a more or less pure state, or whether it was largely 

 composed of crude unsaponifiable matter, or whether it contained any 

 cholesterol at all. As the percentages found were so small, a very slight 

 variation in the amount of impurity present would invalidate and even 

 entirely reverse the conclusions deduced by the author. In a second series 

 of experiments, however, which bring out the increased inhibitory power of 

 the serum of the cholesterol-fed rabbit towards the haemolytic effect of 

 saponin, the results are more satisfactory, and certainly speak for an assump- 

 tion of cholesterol by the blood. But our objection to the method of dosage 

 adopted still holds, and the number of hsemolytic experiments carried out 

 was too few. Our own experiments in comparing the action of sera in this 

 respect have shown us that there is a very considerable variation in the 

 action of the sera of individual animals of the same species, when treated 

 under precisely similar conditions. The discussion of this point, however, 

 we leave for the present, as we hope to make it the subject of a communi- 

 cation in the near future. 



In the experiments we have carried out to ascertain the fate of the 

 cholesterol which disappears from the food we have endeavoured to avoid 

 the difficulties pointed out in the preceding paragraph in the following 

 way : — 



1. We adopted as a standard of comparison a rabbit which was fed for 

 a long period on a cholesterol-free diet, viz., bran thoroughly extracted with 

 ether. The blood of such an animal was compared with that from others 

 which had been fed in an exactly similar way as to times and quantities of 

 extracted bran, but whose food contained in addition a measured daily 

 quantity of cholesterol. In this way we had two rabbits feeding on 

 practically the same diet under the same conditions, and accordingly the 

 chance of variations, especially in the bile flow, due to differences in the 

 food taken was reduced to a minimum, and the only variation likely to 

 interfere was that due to the individual peculiarities of different rabbits 

 which are inevitable in such experiments. 



2. With regard to the estimation of cholesterol in the tissues and the 



