1224 METABOLISM OF LIPOIDS, STEROLS, [pt. iii 



striking thing about the graph is the way in which the free cholesterol 

 diminishes up to hatching, and the cholesterol esters increase. Thus 

 on the 3rd day of development, the free cholesterol makes up 89-9 

 per cent, of the total cholesterol, but on the 21st only 58-68 per cent. 

 Nothing could fit in more strikingly with the results of Hanes. As 

 for the question of a synthesis of cholesterol, Mueller's data do not 

 show any such process to have taken place, but an increase of only 

 1 1 per cent, might, of course, be masked in any but the most careful 

 researches specially designed to test the point. The significance 

 of the fall in total cholesterol found by Mueller after hatching 

 is not evident, but the fact that 

 the cholesterol esters diminish 

 then is in admirable agreement 

 with Hanes' work. Mueller sug- 

 gested that the bile acids might 

 be formed from cholesterol, and 

 this would explain Ellis & Gard- 

 ner's decrease, but the process 

 could hardly be operative on 

 the basis of his own results and 

 those of Thannhauser & Scha- 

 ber. Mueller, in order to carry 

 further the suggestions of Hanes, 

 investigated some embryonic ^ 

 livers separately, and reported '■ 

 that by no means all the cho- 

 lesterol esters were contained 



(bWet weight (Cahn) 

 Cholesberolj* Dry weight (Cahn) 

 (♦Dry weight(Roffo&i 

 Azaretti) 



Days-* 5 



Fig- 390. 



in the liver, nor was the cholesterol of the liver all in the com- 

 bined form. Five 20th-day livers were analysed together, yielding 

 17-9 mgm. of free cholesterol and 51-6 mgm. of combined cholesterol, 

 while in the combined bodies of the 5 embryos, plus the yolk-sac, 

 still partially unabsorbed, there was about 300 mgm. of combined 

 cholesterol. Mueller largely agreed with Hanes' theory, and went 

 so far as to speak of a detoxication of the lipoid fatty acids by com- 

 bination with the cholesterol (why should the released fat be toxic?), 

 but he calculated that a gram of lecithin would produce much 

 more free fatty acid than could be esterified by 100 mgm. of 

 cholesterol. It is not likely that the explanation of the whole process 

 lies in a "detoxication", although there is evidence, such as the 



