Oo the Secretory Cells. 



71 



h erally speaking smaller and less distinct, the lower the mean per- 

 centage of organic matter is in the fluid secreted. 



The cell -granules are in nearly all cases mesostates, i. e. sub- 

 stances stored up in the cell and destined to give rise to the organic 

 substances of the secretion. The granularity of a cell in the resting 

 state thus depends upon its storage -power. Generally speaking the 

 greater the storage -power of a cell, the higher is the percentage of 

 organic substance in its secretion, but this is not always the case, 

 since it may happen that the rate of secretion of water may increase 

 without any corresponding increase in the rate of secretion of organic 

 substance, and in consequence the percentage of organic substance in 

 the secretion may be small; further it is possible that under special 

 circumstances a cell with small storage -power might secrete a large 

 quantity of its stored-up material and that a cell with large storage- 

 power might secrete a very small quantity of its stored-up material, 

 the amount of water secreted by the two cells being approximately 

 equal. 



I all these cells, during active secretion, the following changes 

 take place. The granules decrease in number and usually, if not al- 

 ways, in size; the hyaline substance increases in amount; the network 

 grows. The increase of the network is much less than that of the 

 hyaline substance. 



Moreover in the majority of the cells, the details of the changes 

 which take place are much the same. The hyaline substance increases 

 chiefly in the outer region of the cells, and the granules disappear 

 from this region; so that an outer non -granular zone and an inner 

 granular zone are formed. The network stretches throughout the 

 cell in all cases: in the outer zone its meshes are filled with hyaline 

 substance; in the inner zone its meshes are filled with granules and 

 a small amount of hyaline substance. 



The glands in which an outer non-granular zone is not formed x ) 

 during secretion are, most of the gastric glands of the frog and toad ; 

 the gastric glands of the snake, and the liver of mammals. 



*) The gastric glands of birds have not as yet been examined for the changes 

 occurring in digestion. Cf. however Nussbaum, Arch. f. mie. Anat. XXI. p. 297, 1882 



