I'llS S10L0QY i »F l in I'hil fc I 129 



Tlie copious secretion of pancreatic juice produced I tretin, on I 



une band, and the Bcanty, thick secretion produced by vag tnula- 



tion, on the other, calls to mind .similar differences observed in tin 

 tion of saliva as the resull of chorda-tympani or sympathetic stimulation 

 It will be remembered thai from these latt< nils it was conclu 



thai there must be secretory and trophic fibers concerned in tl trol 



of the activities of gland cells. Interesting corroboration of this conclusion 



lias recently 1 n obtained by histological examination o) tin pancn 



lowing secretin or vagus activity. After the repeated injection oi 

 tin. it is difficult to observe any signs of fatigue in Us; the zymo( 



granules remain practically as numerous as in a resting gland, but in the 

 clear protoplasm of the outer third of the cell, it is said thai fine channels 

 of fluid can be seen. Through these channels water is beli 

 from the blood towards the Lumen and in its course to carry with it some 

 of the zymogen granules, without, however, changing them. Thus, when 

 the gland cells are stained with eosin and orange, afti tretin activity 

 some of the zymogen granules can occasionally 1"- seen in the Lumen of 

 the acini stained with eosin Like those in the cell itself. Aftei 

 stimulation the appearances are different ; no1 only are the granules m 



freely extruded from the cells, but they undergo a preliminary cha; 

 they lose the property of staining with eosin and become stained with 

 orange, at the same time increasing in size so as to form vacm 

 These vacuoles may wander into the ductules, and when they are | 

 here they are stained by orange Figs. 14ii and 147 l I Babkin, etc. Ta ). 



Why there should be both a nervous and a hormone control of the pan- 

 creatic secretion is not clear. This gland, unlike t: trie and salivary 

 glands, is not called upon to become active all of a sudden, and it is dif- 

 ficult to see what could serve as the normal stimulus operating thro 

 the nervous pathway. Taking it all in all, it is probably safe I 

 elude that the nervous mechanism is relatively unimportant, and that 

 under normal conditions it seldom if ever is called into operation I 

 roboration for this view is afforded by the Eaet, above menti 

 the pancreatic juice produced by vagus Btimulatio tryp- 

 sin, which is not the case with normal pancreatic juid 



