2/30 In certain cells an exact balance seems to be maintained, but in those cells whose activity is periodic function takes place at the expense of the cell substance, the loss being restored by nutrition during the period of repose. This is shown particularly well in the case of the nerve cells (Fig. 13). Both the functional and nutritive activity can be greatly stimulated, but they must balance; otherwise the condition is that of disease. In (_a_) the cells and nuclei are shrunken and the smaller clear spaces in the cells are smaller and less evident than in (_b_). |