AGE, GROWTH, AND DEATH 



their secretion and are very conspicuous on account 

 of their dark colour. Three typical cells are repre- 

 sented separately (Fig. 55). The first shows us a cell 



full of the material which is to 

 be discharged and is to form a 

 part of the salivary secretion. 

 The second is a cell which has 

 partly lost its accumulated 

 material, and the third is one 

 which has discharged it almost 

 completely, so that it has be- 

 come very much reduced in 

 size. We learn from these ob- 

 servations and others similar 

 that the size of cells may vary 

 also according to their func- 

 tional condition. Let me refer 

 back to an earlier picture 

 (Fig. 1 6) representing a section 

 of the so-called salivary gland of the intestine, better 

 termed the pancreas. Here we 

 can see for each of these cells a 

 nucleus and a body divided into 

 two parts, a darker portion 

 around the nucleus and a lighter 

 part with little granules in it, 

 which represents the accumu- 

 lation of material which is to 

 form the secretion. When the 

 cells have discharged their secretion, they, like the 



FIG. 54. SECTION FROM AN 

 ORBITAL GLAND OF A DOG 

 After Lavdowsky. 



FIG. 55. DIAGRAM OF 

 THREE CELLS OF A SAL- 

 IVARY GLAND, TO ILLUS- 

 TRATE THE CHANGE RE- 

 SULTING FROM THE DIS- 

 CHARGE OF THE SECRETION. 



