1. Lysosomes were separated from homogenized tissues of the submandibular gland of man and rat by means of ultracentrifugation.

2. The main etiologic factor in chronic Sialadenitis of the submandibular gland is the salivary calculus.

3. In the submandibular gland of Type II, some M-cells showed activity and others did not.

4. We conclude that the Na+–Ca2+ exchange systems of rat pancreatic and submandibular gland acini contribute little to the overall regulation of at rest during cholinergic stimulation.