The Organism and its Protoplasm 1S7 



(6) Details of Cytoplasmic Structure 



Concerning the details of structure of these two main 

 classes of cell material, Wilson writes : "As ordinarily seen 

 under moderate powers of the microscope, protoplasm ap- 

 pears as a more or less vague granular substance which 

 shows as a rule no definite structure. More precise exam- 

 ination under high powers, especially after treatment with 

 suitable fixing and staining reagents, often reveals a highly 

 complex structure in both nucleus and cytoplasm. Since 

 the fundamental activities of protoplasm are everywhere of 

 the same nature, investigators have naturally sought to 

 discover a corresponding fundamental morphological or- 

 ganization common to all forms of protoplasm and under- 

 lying all its special modifications. Up to the present time, 

 however, these attempts have not rtesulted in any con- 

 sensus of opinion as to whether such a common organization 

 exists. In many forms of proto])lasm, both in life and 

 after fixation by reagents, the basis of the structure is a 

 more or less regular framework or meshwork, consisting of 

 at least two substances. One of these forms the substance 

 of the meshwork proper: the other, often called the ground- 

 substance, (also cell-sap, enchylema, hyaloplasma, parami- 

 tome, interfilar substance, etc.), occupies the intervening 

 spaces. To these two elements must be added minute, deep- 

 ly-staining granules or 'microsomes' scattered along the 

 branches of the meshwork, sometimes quite irregularly, some- 

 times with such regularity that the meshwork seems to be 

 built of them. Besides the foregoing three elements, which 

 we may provisionally regard as constituting the active sub- 

 stance, the protoplasm almost invariably contains various 

 passive or metaplastic substance in the form of larger gran- 

 ules, drops of liquid, crystalloid bodies, and tlio like. These 

 bodies, which usually he in the spaces of the meshwork, are 

 often difficult to distinguish from the microsomes lying in 



