192 W. R. BLOCK 



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

 duces soap enough to emulsify the whole amount and thus prepare it for 

 the action of the intestinal lipases. 



The Li pases of the. Intestinal Tract and Digestion. Lipases are se- 

 creted into the intestine mainly by the pancreas, although Boldiroft' has 

 found that the intestinal secretions contain a lipaso acting on emulsified fat 

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

 by bile. Boldireff tested lipolytic action with monohutyrin, milk and 

 olive oil (Jansen objects to the use of monobutyrin because it is split 

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

 butyrinase fan esterase] is involved). The lipolytic activity of intestinal 

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

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

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

 the presence of food, secret in, acids and soaps. In general, the amount 

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



The excitants for the secretion of pancreatic juice are normally acids 



+ 



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

 ably by the formation of secret in, rather than by reflex action on the 

 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 is 

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

 secretion. By the time it reaches the intestine food fat normally contains 

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

 alkali of the intestinal secretions. Water acts mainly indirectly by stim- 

 ulating acid gastric secretion. The nervous system undoubtedly also 

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

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



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

 found to vary greatly, the average from normal dog* (Pawlow and co- 

 workers) obtained by pancreatic fistula being about 2'2 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 

 glyeerol, 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 condition? by which an ex- 

 cellent synthesis may be accomplished. By using oleic acid homogenized 

 with glycerol and mixed with glyeerol extract of pancrea? (therefore with 

 excess of glyeerol) 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 mainly 

 the triglycerid. Armstrong and Gosney have made an exact study 



