Destiny of Cholesterol in the Animal Organism. 



235 



Discussion of Results. — Dealing only with the results of the first two 

 weeks, it will be seen from the table that, on the ordinary diet, the total 

 cholesterol decreases by about 15 per cent, during the first week, and then 

 increases again during the second week to within about 6 per cent, of the 

 value in the day-old chick ; the free cholesterol shows a similar decrease 

 during the first week, but at the end of the second week has increased again 

 to the original value. The ester cholesterol also decreases by about 17 per 

 cent, during the first week, but the decrease is much less marked during the 

 second. 



In the case of animals fed on the extracted diet, there is a decrease in the 

 total cholesterol during the two weeks, but the decrease during the first week 

 is nearly double that in the second. This variation in the rate of decrease 

 appears to be due to the ester cholesterol, which shows a marked decrease 

 during the first week, but only a slight change during the second. The free 

 cholesterol goes down fairly steadily. 



In the case of the animals fed on extracted food + cholesterol, the total 

 cholesterol increases during the two weeks, more markedly in the second 

 than in the first. The cholesterol thus stored up is mainly in the form of 

 esters ; these show a marked increase during the two weeks, the increase in 

 the second being double that in the first. The free cholesterol does not 

 appear to be much afl'ected ; the figures are of much the same order as in the 

 case of the animals on ordinary diet, the main difference being that the 

 decrease noticed during the first week is less marked. 



It will be noticed that the rate of growth of the animals in the earlier 

 weeks on the cholesterol diet was slower than in the other cases, but we 

 have no means of forming an opinion as to whether this is due to the diet, or 

 to the amount of food eaten, or to the individuality of the animals. The 

 day-old chicks, however, in this case were smaller than in the others. 



What is the meaning of the high free cholesterol content in the fourth 

 week of the experiment with extracted food we are unable to say, but we 

 cannot attach much value to this particular result for the reasons already 

 stated. 



The cholesterol content of the chickens thus appears to depend on the 

 sterol content of the diets, but there is nothing in the figures of the first two 

 weeks to indicate that in the growing animal the organism can synthesise 

 cholesterol. We have not carried out this investigation in as detailed a 

 manner as was intended at the outset, as the animals did not prove very 

 suitable for the investigation of problems of growth, partly owing to the 

 habits of the birds, rendering it very difficult to control the amount of food 

 taken, and to estimate the excrement, and partly owing to the difficulty of 



