1. The biosynthesis and extracellular liberation off alpha-amylase by cultures of B. subtills in the presence of a number of carbon sources has been investigated. 2. Small amounts of extracellular amylaso were released before the end of the logarithmic phase of growth. 3. Under continuous culture growth conditions, only very small amounts of extracellular amylase were produced during growth on starch-containing media. 4. B. subtilis amylase can be effectively purified by specific complex formation with glycogen. 5. Some of the properties of B. subtilis amylase and commercial amylases claimed to be preparations from B. subtilis have been investigated and the two shown to differ appreciably with respect to heat stability and pattern of attack on amylase. 6. An insoluble derivative of amylase, CN-Cellulose-alpha-amylase, has been prepared and the combination of the enzyme with the cellulose macromolecule has been shown to alter the characteristics and mode of action of the enzyme. An attempt has been made to interpret these effects.