ABSORPTION AND TRANSPORT OP FATS 167 



Bollman and associates 781 adduced direct evidence that lipids are trans- 

 ported primarily via the thoracic duct. The concentration of lipids was 

 found to increase enormously in the intestinal and thoracic duct lymph of 

 the dog after the feeding of a fatty meal or of one containing free fatty 

 acid or oleic acid; the increase could be traced largely to neutral fat. On 

 the other hand, the concentration of fatty acids in the hepatic lymph was 

 lower than that from the thoracic duct or from the intestine ; moreover, it 

 did not increase after fat feeding. 



(a) The Comparative Composition of Ingested and Lymph Fat. It has 

 already been shown that the lymph may contain triglycerides after fatty 

 acids or monoglycerides have been fed. 768 There is also evidence that 

 changes in the nature of the fatty acids may likewise obtain in the lymph 

 fat as contrasted with the acids fed. It is suggested by Bloor 35 that these 

 conditions may be traced to: (1) a selective absorption of certain fractions 

 (usually the lower-melting) by the intestinal cells, (2) other changes in the 

 nature of the additions of body fat, or (3) chemical changes such as 

 saturation or desaturation which may alter the composition. 



Several examples of the different compositions of food and lymph fats 

 may be cited. Munk 782 found a higher melting point in the fecal fat than 

 in the original food fat. When cetyl palmitate was given, the chyle fat 

 was shown to consist of one part of triolein and 6 parts of tripalmitin with a 

 melting point of 36°C. 620 Frank reported 36% of olein in chyle fat 679 after 

 the feeding of ethyl palmitate, while, after the feeding of mutton tallow 

 (m.p., 51.7°C), the chyle fat melted at 38°C. 783 On the other hand, 

 Bloor 784 - 785 obtained chyle fat having a higher melting point than the in- 

 gested food fat. After the administration of olive oil in which the fatty 

 acids melted at 16°C, fat melting at 30°C. was obtained from the chyle. 

 Similar results are reported by Raper. 786 



According to Bollman et al., 781 the phospholipids increased three-fold 

 in lymph as the result of fat feeding ; this was associated with the maximal 

 increase found in neutral fat. "Since the increase in phospholipids occurs 

 in the intestinal and thoracic duct lymph, and not in the hepatic lymph, 

 it is suggested that this fact affords proof of the synthesis of this material 



781 J. L. Bollman, E. V. Flock, J. C. Cain, and J. H. Grindlay, Am. J. Physiol., 163, 

 41-47 (1950). 



782 1. Munk, Arch. path. Anat. Physiol. (Virchow's), 122, 302-325 (1890). 



783 0. Frank, Arch. Physiol. (Du Bois-Reymond's), 1894, 297-308. 



784 W. R. Bloor, J. Biol. Chem., 15, 105-117 (1913). 

 788 W. R. Bloor, /. Biol. Chem., 16, 517-529 (1914). 

 786 H. S. Raper, J. Biol. Chem., 14, 117-134 (1913). 



