282 ABSORPTION 



These authors mixed 157*3 grm. blood containing 0'04 per 

 cent, fat with 31*7 grm. chyle containing 2*607 per cent. fat. 

 The total fat of the mixture was reckoned then at 0*889 grm. 

 Analysis, however, gave 0'225 grm. In other words, 74*2 per cent, 

 of the fat had disappeared. 



The essential conditions for this action of the blood are (1) 

 the presence of the red corpuscles the serum does not act ; (2) 

 the presence of oxygen ; (3) a very fine emulsion of the fat (milk 

 is too coarse). The velocity of the reaction at 40 C. is double 

 that at room temperature. Watery extracts of blood which has 

 been dried at 40 C. produce the effect, but not so if from blood 

 dried at 100 C. 



This action of the blood on fat is not the same as that of 

 pancreatic lipase, and it cannot correctly be termed a lipolytic 

 action. What the fat changes into is unknown, but the products 

 are insoluble in ether, soluble in water and dialysable. Soaps 

 are probably formed to a certain extent, but not in amount 

 corresponding to that of the fat disappearing. 



Hanriot, by studying the action of serum on mono-butyrin, 

 has been led to ascribe a lipolytic action to this fluid. Experi- 

 mental results obtained with so simple an ester as mono-butyrin 

 cannot be safely applied to the neutral fats. Mono-butyrin is 

 split both by the action of the sodium carbonate, and by that 

 of the proteids of the serum, and there is no evidence that a 

 lipase really exists in the serum. 



Since the depot fat in the tissues can both wander in and 

 wander out, according to the metabolic needs of the body, the 

 tissue cells must possess the power of splitting and dissolving 

 fats as well as the power of synthesis, for there is no reason to 

 think that fat in the droplet form can pass out of the depots 

 into the blood stream, any more than it can pass in the reverse 

 directions. Extracts of minced liver, intestinal mucosa, muscles, 

 &c., have at any rate the power to split mono-butyrin, and after 

 oil has been injected into the substance of the muscles of an 

 animal, fat drops are found within the sarcolemma, which suggests 

 that the fat has been dissolved, absorbed, and resynthesised (Hester). 



To sum up, then finely emulsified fat is split in the stomach, 

 and other fat in the intestine. The products, soap and fatty 

 acid, dissolved by the bile, are absorbed and built again into 

 neutral fat by the intestinal mucosa. It is probable that 



