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A MANUAL OF VETERINARY PHYSIOLOGY 



condition, and the cells are seen crowded with granules ; these are 

 so arranged that the margin presents a clear or fairly clear zone, 

 while within this there is an intensely granular zone (Fig. 83, A). 

 The minute granules filling the cell are the mother-substances 

 of the secretion. When activity commences the granules appear 

 to pass centrally towards the alveolus, leaving the cell com- 

 paratively clear excepting that portion immediately abutting 

 on the alveolus, which even in the exhausted condition remains 

 granular. These changes result in the cells becoming distinct and 

 clearly defined, and, moreover, as they have emptied their 

 granular contents into the alveolus as pancreatic secretion, they 

 have consequently become much smaller. The narrow clear zone 

 seen in the resting gland has now become broad, the previously 



Fig. 83. -A Portion of the Pancreas of the Rabbit (Kuhne and Sheridan 

 Lea). A, at Rest ; B, in a State of Activity (Foster). 



a, The inner granular zone in A is larger and more closely studded with fine 

 granules than in B, in which the granules are fewer and coarser, b, The outer 

 transparent zone is small in A, larger in B, and in the latter marked with 

 faint striae, c, The lumen is very obvious in B, but indistinct in A. d, An 

 indentation of the junctions of the cells seen in the active but not in the 

 resting glands. 



choked alveolus is clearly defined, whilst the nucleus of the cell, 

 which was hidden in the charged condition, can easily be seen in 

 the exhausted gland (Fig. 83, B). These changes have been 

 worked out on the pancreas of the living rabbit by Kuhne and 

 Sheridan Lea. 



Amount of Secretion. — From the investigations of Colin and 

 others we know that in most animals the secretion of pancreatic 

 juice is continuous, though not uniform. In ruminants the 

 largest secretion is towards the end of rumination ; in the dog 

 the maximum is reached between the second and fourth hours 

 after feeding, this maximum being followed by a fall, and about 

 the seventh hour by a rise. It will be remembered that the bile 

 gives a similar curve. In the dog it is generally considered there 

 is no secretion during starvation, but immediately food begins 



