DEGENERATIONS AND INFILTRATIONS. 275 



connective-tissue cells that have undergone extensive fatty infiltra- 

 tion. A transitory fatty infiltration is also normal in the cells of 

 the liver (Fig. 248). 



FIG. 248. 



Cells from the human liver, normal. (Orth.) a, cells free from fat. The isolated cell to the 

 right contains two nuclei and three or four granules of pigment. The three lower cells, 

 6, are infiltrated with globules of fat. It will be noticed that those three cells contain as 

 much cytoplasm as the two contiguous cells, a. This is taken as an indication that the 

 fat is superadded to the cytoplasm, and has not been produced at the expense of part of 

 the organized substance of the cell. This does not imply that the fat was necessarily 

 taken into the cell as such, for it may have been produced within the cell from food-mate- 

 rials ; but it has not been produced at a sacrifice of the organized materials forming an 

 essential part of the living cell. 



The globules of fat form a part of the metaplasm of the cells in 

 which they are situated ; i. e., they do not constitute an integral 

 part of the cytoplasm, but lie within it, leaving it intact, unless the 

 accumulation is so great that the functions of the cell are interfered 

 with. Then the cytoplasm may suffer atrophy and its usefulness be 

 diminished. 



It is not possible to lay down any practical rule for distinguishing 

 between fatty infiltration and fatty degeneration when cells are 

 examined under the microscope, beyond the general statement that 

 in degeneration there is a corresponding destruction of the cyto- 

 plasm as the fat accumulates. In fatty infiltration the globules of 

 fat are rather more apt to coalesce with each other than in fatty 

 degeneration, so that the globules appear larger. This is not in- 

 variably the case, however, the behavior of the fat in this respect 

 differing in different kinds of cell. 



4. Glycogenic Infiltration. This is a condition analogous to fatty 

 infiltration, but the stored excess of food-material in this case be- 

 longs to the class of carbohydrates. The condition is found in the 

 cells of the convoluted renal tubules in cases of diabetes mellitus, 

 sometimes in the leucocytes in inflammatory foci, and occasionally 

 in the cells of tumors where the functional activities of the cells 

 are in abeyance and only their formative powers call for a consump- 

 tion of food. 



