Abstract
The existence of early or mild states of deficiency diseases has been demonstrated by some of the newer more sensitive methods of biochemistry, x-ray and biomicroscopy. Various stages of disease may be classified according to form, intensity and duration. These stages progress or regress as modified by changes in diet or therapy and may be complicated by acute conditions being superimposed on chronic states. Biochemical and bio-microscopic evidence of the state of the disease do not necessarily rise and fall concurrently. Therefore in determining the length of time that treatment should be continued, a recognition of any chronic condition is very important.