Data are presented to show that this PAS-positive mucoprotein can be demonstrated by metachromatic staining with toluidine blue after the mucoprotein is sulfated. This procedure indicates that mucoprotein is also present in a granular form in all nerve cells in both senile and young dogs.

The evidence for this is further substantiated by the use of the aldehyde-fuchsin stain following both periodic acid oxidation and sulfation. The granular and non-granular deposition can be demonstrated by the periodic acid-aldehyde-fuchsin method due to the affinity of the aldehyde-fuchsin stain for aldehydes. It can be demonstrated following the sulfation-aldehyde-fuchsin method owing to the affinity of the stain for the sulfuric group. The evidence for this latter phenomenon has been reported by Scott and Clayton (6).

It is concluded that mucoprotein is present in a granular form in all nerve cells in both senile and young dogs but is not concentrated enough in the latter to be demonstrated by the PAS method.