AbstractVarious histochemical tests were performed to study the nonenzymatic components of lysosomes in the neurons of rat spinal cord. The lysosomal granules are periodic acid Schiff positive and this reaction can be blocked by acetylation, but not by bromination. They are performic and peracetic acid Schiff positive also. Both these reactions can be blocked by bromination. It is concluded that 1:2 glycol as well as ethylene groups are present. Lysosomes stain metachromatically after sulfation and are sudanophilic. They are chemical complexes containing protein, neutral polysaccharide, phospholipids and possibly glycolipids and are present in dendrites as well as axons. A topographical relationshiop exists between lysosomes and Golgi apparatus which was stained with nucleoside diphosphatase method. Lysosomes share Schmorl reaction with lipofuscin pigment. In some preparations there is a tendency for them to be localized along the cell membrane.