36 STRUCTURAL COMPOSITION OF HUMAN BODY. 



almost infinitely various, according to the position, office, 

 and age of the cell. In adipose tissue they are the oily 

 matter of the fat; in gland-cells, the contents are the 

 proper substance of the secretion, bile, semen, etc., as the 

 case may be ; in pigment-cells they are the pigment gra- 

 nules that give the colour ; and in the numerous instances 

 in which the cell-contents can be neither seen because they 

 are pellucid, nor tested because of their minute quantity, 

 they are yet, probably, peculiar in each tissue, and con- 

 stitute the greater part of the proper substance of each. 

 Commonly, when the contents are pellucid, they contain 

 granules which float in them ; and when water is added 

 and the contents are diluted, the granules display an active 

 molecular movement within the cavity of the cell. Such 

 a movement may be seen by adding water to mucus-, or 

 granulation-corpuscles, or to those of lymph. In a few 

 cases, the whole cavity of the cell is filled with granules : 

 it is so in yelk-cells and milk-corpuscles, in the large 

 diseased corpuscles often found among the products of 

 inflammation, and in some cells when they are the seat of 

 extreme fatty degeneration. All cells containing abundant 

 granules appear to be either lowly organized, as for nutri- 

 ment, e.g., yelk-cells, or degenerate, e.g., granule-cells of 

 inflammation, or of mucus. The peculiar contents of cells, 

 may be often observed to accumulate first around or 

 directly over the nuclei, as in the cells of black pigment, 

 in those of melanotic tumours, and in those of the liver 

 during the retention of bile. 



Intercellular substance is the material in which, in certain 

 tissues the cells are imbedded. Its quantity is very 

 variable. In the finer epithelia, especially the columnar 

 epithelium on the mucous membrane of the intestines, it 

 can be just seen filling the interstices of the close-set cells ; 

 here it has no appearance of structure. In cartilage and 

 bone, it forms a large portion of the whole substance of 

 the tissue, and is either homogeneous and finely granular 



