1 196 



FAT METABOLISM 



[PT. Ill 



posed in the past. Imrie & Graham, however, in view of the sudden 

 and rapid decrease in the Hver fat after birth, thought it likely that 

 it was utilised for some special purpose then, which may well be the 



• Embryonic 

 o Maternal 



They next proceeded to mobilise the fatty acids of the body by 

 giving phloridzin and by subjecting the animals to a fast. The results 

 were as shown in Fig. 371. Evidently phloridzin and fasting will 

 produce a fatty infiltration of the embryonic liver. The graph also 

 shows that treatment which will not very greatly affect the maternal 

 liver will have a considerable effect on that of the embryo. From 

 the data on the iodine value it can be seen that, simultaneously with 

 the entry of fresh fat into the 

 embryonic liver, the iodine 

 value of the liver fat falls, just 

 as would be expected if such 

 fat was coming in from the 

 other tissues. Here again the 

 maternal liver is hardly in- 

 fluenced. Experiments similar 

 to the foregoing were carried 

 out on pregnant guinea-pigs 

 with embryos over 40 gm. in 

 weight, and from these it ap- 

 peared that the physiological 

 infiltration of about 15 gm. 



30 10 



gms. weight, embryos 



Fig. 371. The normal data are here represented 

 by continuous lines; the phloridzin data by 

 points not joined together. 



per cent, is by no means the maximum capacity of the embryonic 

 liver, for by means of phloridzin the amount was raised to as 

 much as 30-49 per cent, (wet weight). These experiments showed 

 that phloridzin must pass the placenta, and make it highly probable 

 that the physiological fatty infiltration is not derived from the tissue 

 fat but some other source. Perhaps this other source is that postulated 

 by Wesson in his explanation of the increasing fat-content of the 

 embryonic body and the impermeability of the placenta to fatty 

 acids. 



One of the statements which has entered the literature without 

 much justification is that embryonic cells (and carcinoma cells too) 

 will not show fatty infiltration when treated with phosphorus. This 

 was said to be the case by Hess & Saxl who made in vitro experiments 

 on guinea-pig and rabbit tissues (liver and kidney) . Some years later 



