Feeding growing rats a diet deficient in magnesium results in a deficiency condition whose major characteristic, that of kidney calcification, exhibits a mechanism very similar to that of urolithiasis in humans. Work done with lysosomal stabilizers and rats fed this deficient diet shows a reduction in calcification with the administration of these drugs. Accordingly, a study was undertaken to examine the mechanism of this process more closely with regards to a possible involvement of kidney lysosomes or the vacuolar apparatus. Lysosomal enzyme levels in the kidneys of rats fed either a low magnesium or a control diet were examined and an attempt made to determine if there were any differences due to treatments. While biochemical evidence suggests no differences, histochemically we see what appears to be a shift in activity to the area where calcification occurs. At the same time, while there is no effect from treatment, there appears to be a time effect, enzyme activity decreasing or increasing significantly with day. This seems to appear histochemically in the form of increased PAS sustainability in sections from rats on either low magnesium or control diet compared to rats on a rat pellet diet. / Master of Science