;HAP. III.] THE PANCREAS AT REST AND IN ACTION. 197 



5. In dogs, atropia stops the secretion of pancreatic juice, but 

 lot in rabbits (Paw low). Pilocarpin induces a sluggish secretion 

 >f concentrated juice (Heidenhain). Curare, according to Bernstein, 

 increases the flow of pancreatic juice, but according to Heidenhain 

 merally diminishes it. 



[eidenhain's From the analogy to the salivary glands Heiden- 

 leoreticai ham thinks it likely that in the pancreas as in the 

 s as to salivary glands there exist two classes of secretory 

 nerves of nerves which influence activity, viz. truly secretory, i.e. 

 ie pancreas. wn i cn govern the separation of water by the gland, 

 id trophic, which by influencing the exchanges of matter in the 

 jcreting cells, influence the passage of solid constituents into the 

 jretion. 



Circulatory Bernard pointed out that the fasting pancreas is 



jes in the pale, the active pancreas firm and turgid ; and Kiihne 

 icreas. an( j L ea have observed the circulatory changes going 



>n in the pancreas of the living rabbit which are referred to in 

 ie subjoined paragraph. 



Changes in the appearances of the secretory cells which accompany 

 secretion. Concomitant vascular changes. 



Our knowledge of the remarkable changes which the secretory 

 Ls of the pancreas undergo during digestion is derived first of all 

 >m the researches of Heidenhain 1 , which have been confirmed 

 the remarkable observations made by Kiihne and Lea 2 , who were 

 ible to watch the actual process of pancreatic secretion in the case of 

 ie transparent pancreas of young rabbits, which was drawn through 

 small wound in the abdominal wall, and examined under the 

 dcroscope, special arrangements being employed, which prevented 

 evaporation and cooling. The following is a short but admirable 

 summary by Professor Michael Foster of both Heidenhain's and 

 Kuhne and Lea's researches : 



' We learn from the researches of Heidenhain that each secreting 

 cell of a pancreas of an animal (dog) which has been fasting for 30 hours 

 or more consists of two zones: an inner zone, next to the lumen of the 

 alveolus, which is studded with fine granules, and a smaller outer zone, 

 which is homogeneous or marked with delicate striae. Carmine stains 

 the outer zone easily, the inner zone with difficulty. The nucleus, more 

 or less irregular in shape, is placed partly in the one and partly in the 

 other zone. When however the pancreas of an animal in full digestion 

 (about six hours after food and onwards) is examined, the outer homo- 

 geneous zone is found to be much wider, the granular inner zone being 



1 Pfliiger's Archiv, x. (1875), p. 557. 



2 Kiihne u. Lea, ' Beobachtungen iiber die Absouderung des Pankreas.' Verhand. 

 d. Naturhist. Med. Vereins zu Heidelberg, Bd. i. 1877, Heft 5, aud Unters. a. d. physiol. 

 lust. Bd. u. S. 448. 



