THE CELL 



95 



It is further found difficult to say what granules actu- 

 ally belong to the substance of the cytoplasm or may be 

 temporarily harbored by it. Thus in many cells of the 

 higher animals we find granules that are reserve stuffs 

 held by the cells until needed elsewhere. In the cells 

 of the resting salivary gland large numbers of granules 

 are found which are absent after the gland has been for 

 some time active. These granules, used up during the 



Cftromat'n 



J/inin 



flue tear fluid 

 JVucleqrmetnbrane- 



tz.-^. Chromdfta HefHnot: 



Joreiyfi inclosupes jbfefoplt&m 

 FIG. 29. Diagram of a cell. (Huber,) 



glandular activity, were composed of the antecedents 

 of substances supplied by the cells to the glandular secre- 

 tion, were products of cellular activity, but were not 

 components of the essential vital structure of the cyto- 

 plasm. In the cells of the liver it is common to tind 

 globules of fat and glycogen especially after a meal rich 

 in fats and carbohydrates, but being temporarily present 

 they cannot be essential components of the cytoplasm. 



