CELL-GRANULES. 25 



pletely filled and distended with a solid mass of fat, the 

 original protoplasm remaining only as a thin atrophied shell. 

 In plant-cells the body of the cell is largely occupied by sap, 

 starch-granules, and the like. In some cases the protoplasm 

 becomes transformed, so that little vitality is left to the cell ; 

 as in the horny layer of the skin, in which the cells have been 

 converted into a tough horny substance well adapted to pur- 

 poses of protection. 



Cell-granules : The granules which occur in the bodies of 

 many cells are of various kinds. Some are particles of pig- 

 ment produced by the action of the cell or absorbed from 

 without. Some are produced artificially by the reagents em- 

 ployed in the preparation of the specimen, not occurring in 

 the natural state ; even water will cause the appearance of 

 granules in some cells. Other granules, which are colorless, 

 appear to be specializations of the body-protoplasm. Among 

 such granules important distinctions are made out, especially 

 by their behavior with staining-reagents ; these distinctions 

 are especially serviceable in the study of leukocytes. Some 

 granules will become stained by one kind of dye, others by 

 another kind, these staining-peculiarities corresponding to dif- 

 ferences in the chemical constitution of the granules. 



Stains in which the coloring-agent is the acid part of the 

 compound, as eosin, are called acid stains ; those in which the 

 basic portion of the dyestuff is the staining-principle, as 

 methylene-blne, are called basic stains; while stains composed 

 of a mixture of acid and basic dyes are called neutral stains. 



Granules which are colored by neutral stains are called 

 " neutrophile " ; those that take basic stains are called " baso- 

 phile " ; those that take acid stains are best called " oxyphile " 

 f oc'JC, acid, and ydeco, to love), though they are most com- 

 monly called "eosinophile " (eosin being one of the most potent 

 acid stains), also sometimes " acidophile " (a barbarous term). 



Ehrlich's much-quoted division of the granules of leuko- 

 cytes and other cells into five classes is as follows: ^.-granules, 

 coarse oxyphilic or eosinophilic granules, found in certain 

 human leukocytes; /2-granules, amphophilic granules (taking 

 both acid and basic stains), occurring in the blood of some 

 animals ; y-granules, coarse basophilic granules, found in mast- 

 cells ; ^-granules, fine basophilic granules, at times found in 



