Calcification in Molluscs. III. Intake and Deposition of Ca45 and P32 in Relation to Shell Formation

1. Both fresh water and marine molluscs take up labeled calcium and phosphorus from the water. 2. Labeled calcium is concentrated on the periphery of the mantle and also is incorporated into the crystals of calcium carbonate in the newly formed shell. 3. Labeled phosphate was localized on the inner margin of the mantle in the region of the mucus glands. It was also incorporated in the periostracum surrounding the crystals. 4. The phosphatase and phosphate present in the mantle are concerned with a phosphorylating process; the significance of this phenomenon in relation to mineralization is not clear.