The mucin of the salivary glands of the chiken was examined histochemically. The results obtained are as follows.
(1) In all the salivary glands, the contents of the glandular cell and the secretion in the glandular lumen were strongly periodic acid-Schiff reactive, azure A-metachromatic at a low value of pH, and alcianophilic, and showed affinity to various acid mucin stains. Methylation completely deprived the glandular cell of such properties as alcianophilia and metachromasia. Saponification after methylation almost completely restored those properties blocked by methylation. Digestion with such an enzyme as diastase, hyaluronidase, or sialidase failed to modify the staining properties of the glandular cell. The cell was almost negative for ninhydrin-Schiff and mercuric bromphenol blue reactions for protein. From the results of these histochemical reactions, it was concluded that the salivary glands of the chiken were all mucin-secreting ones, and that the mucosubstance contained in the glands was acid mucopolysaccharide in nature.
(2) The acid mucin of the salivary glands was considered as compounds of nonsulfated and sulfated acid mucopolysaccharide. It was different in composition from one gland to another. The salivary glands were divided into two groups on the basis of this difference. The maxillary, anterior lingual, and angulus oris glands were composed mainly of nonsulfated acid mucopolysaccharide and classified into
one group. The palatine, anterior and posterior submandibular, spheno-pterygoid, posterior lingual, and crico-arytenoid glands consisted mainly of sulfated acid mucopolysaccharide and formed the other group.