HISTOLOGY 



PROTOPLASM. 



Protoplasm is the living substance of which cells are composed. More 

 specifically the term is applied to this living substance exclusive of the 

 nucleus, or to the corresponding dead material, provided that death has 

 not changed its physical properties. It has been proposed to substitute 

 the name cytoplasm for protoplasm in the restricted and earlier sense of 

 the term, to call the nuclear substance karyoplasm, and to consider both 

 cytoplasm and karyoplasm as varieties of protoplasm. Although these 

 names are often employed, the cell substance apart from the nucleus is 

 ordinarily called protoplasm. 



Protoplasm is a heterogeneous mixture of substances forming a soft 

 viscid mass of slightly alkaline or neutral reaction. ("The terms may 



Centrosome. 



Emulsion structure. 



Droplet'in emulsion. 



Nuclear membrane. 



Linin. 



Nuclear sap. 



Spongioplasm. 



Hyaloplasm. 



Chromatin cord. 



Chromatin knot. 



Exoplasm. 



Cell membrane. 



Granules 



FIG. r. DIAGRAM OF A CELL. 



In the four quadrants different types of protoplasmic structure are represented namely, homogeneous, 



granular, foam-like, and fibrillar. 



be used interchangeably for an alkalinity which is so slight" Henderson.) 

 It is ordinarily more than three-fourths water, and the remainder con- 

 sists of salts and organic substances, some in solution and some in a colloidal 

 state. The organic bodies are classed as proteins, glycogen or some allied 

 carbohydrates, and lipoid (fat-like) bodies. Protoplasm may exist in a 

 numberless variety of forms. 



On microscopic examination, even with lenses of the highest power, 

 the protoplasm of certain living cells appears homogeneous and structure- 

 less. But most of the cells which the histologist examines are not living. 



