SECT. I l] 



FAT METABOLISM 



1169 



acids and the total alcohol-ether extract rose in grams per cent, wet 

 weight, the latter remained quite constant in per cent, dry weight. On 

 the other hand, the total fatty acids did show a rise, similar to Murray's. 

 Fig. 362 shows this, but it only means that some differences be- 

 tween the techniques used by Murray and by Cahn, which, owing 

 to the lack of detailed information in their papers, we cannot exactly 

 define, caused discrepancies in the earlier stages. In any case, the 



O Murray (bobal ether alcohol extract) 



• Cahn f total ether alcohol extract) 



♦ Cahn (total fatty acids) 

 ® Cahn (triglyceride fatty acids) 



Cahn 



Days-> 5 10 



Fig. 363 



total alcohol-ether extract is not an entity of great interest. Cahn's 

 figures for triglyceride fatty acids are shown in Fig. 362, expressed 

 in per cent, of the dry weight of the embryo. Here the rise is un- 

 doubted, and it is significant that the usual 14th day inflection 

 appears on the curve. 



If the daily increment is plotted, an interesting bell-shaped curve 

 appears. As Fig. 363 shows, 100 gm. add on to themselves more 

 and more fatty acids (triglycerides) until the 19th day, after which 

 there is a slackening off. This agrees well with the absorption in- 

 tensity curve for fat as shown in Fig. 251. Cahn's interesting com- 



