96 



BIOLOGY: GENERAL AND MEDICAL 



actual source of the cell life; but his view has been 

 abandoned, and we now suppose that the granules of 

 the spongioplasm are composed of those substances 

 formed by the living substances and useful in its 

 various activities. From this point of view these 

 granules are not permanent structures, but appear and 

 disappear as they are prepared or employed. 



Etofibsm ____ 



Joreya inciosutes 

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



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 

 glandular activity, were composed of the antecedents 

 of substances supplied by the cells to the glandular secre- 



