192 W. R. BLOCK 



acid present which, uniting with the alkali of the intestinal secretions, pro 

 daces soap enough to emulsify the whole amount and thus prepare it fc 

 the action of the intestinal lipases. 



The Lipases of the Intestinal Tract and Digestion. Lipases are 

 creted into the intestine mainly by the pancjeas, although Boldireff hi 

 found that the intestinal secretions contain a lipase acting on emulsified fa 

 which is different from pancreatic lipase in that its action is not accelerate 

 by bile. Boldireff tested lipolytic action with monobutyrin, milk 

 olive oij (Jansen objects to the use of monobutyrin because it is sj 

 by water alone and because in all probability a different ferment, monc 

 butvrinase [an esterase] is involved). The lipolytic activity of intcstii 

 juice is ordinarily slight, and in the presence of normal pancreatic seci 

 tion is probably not an important factor in fat digestion. Bile increas 

 its activity. The flow of secretion in fasting is small and is increased 

 the presence of food, secretin, acids and soaps. In general, the amc 

 of secretion is less the farther away from the duodenum it is collected. 



The excitants for the secretion of pancreatic juice are normally acic 



+ 



(H), fats and water; alkalies have a retarding action. Acids act prol 

 ably by the formation of secretin, rather than by reflex action on 

 intestine, as Pawlow believed, although stimulation of the nerve supply 

 will cause secretion. Fats are found. to act as excitants only when partially 

 saponified, and soap is probably therefore the active substance which 

 rendered the more likely since soap has been found by Fleig to produce 

 secretion. By the time it reaches the intestine fcod fat normally coiitaii 

 enough free fatty acid to form a considerable amount of soap with 

 alkali of the intestinal secretions. Water acts mainly indirectly by stii 

 ulating acid gastric secretion. The nervous system undoubtedly als 

 plays an important part in pancreatic secretion not only as a regulat 

 but also in the production of the secretion (Bylina, 1911). 



The amount of pancreatic juice secreted in a 24-hour period has 

 found to vary greatly, the average from normal dogs (Pawlow and 

 workers) obtained by pancreatic fistula being about 22 c.c. per kilo per 

 24 hours. For human beings the amount is reported to be about 600 c.c. 

 per day. 



The pancreatic lipase (steapsin) hydrolyzes the fats to fatty acids and 

 glycerol, an action which is reversible, as was first reported by Pottevin, 

 later confirmed by Taylor and Hamsik (a) (1909), and finally more con- 

 clusively by Foa (a), who determined the exact conditions by which an ex- 

 cellent synthesis may be accomplished. By using oleic acid homogenized 

 with glycerol and mixed with glycerol extract of pancreas (therefore with 

 excess of glycerol) he was able to get a synthesis of about 62 per cent of the 

 oleic acid used in 50 hours at 38 C. The compound formed was mainb 

 the triglycerid. Armstrong and Gosnev have made an exact stuc 



