Malt amylase is not a single enzyme, but a mixture of 2 enzymes, dextrinogen amylase (DA.) and saccharogen amylase (S.A.), which are distinguished by their action and their stability. The dextrins dominate among the starch hydrolysis products produced by D.A. If starch is hydrolyzed with S.A.. maltose is the chief product even from the beginning. During dialysis of a malt solution the D.A. is practically destroyed at a time when the S.A. retains about 1/2 of its original activity. At low temperatures and low pH the S.A. is appreciably more stable than the D.A. Under alkaline conditions the D.A. is slightly more stable than the S.A. At higher temp. the D.A. is decidedly more stable than the S.A. If a malt solution is acidified with HCl to pH 3.3 and brought to pH 6 with secondary Na phosphate after 15 min. the D.A. is practically completely destroyed while 70-80% of the activity of the S.A. remains. If a malt solution of pH 7.6 is heated for 15 min. at 70[degree] the S.A. is practically destroyed while the D.A. retains 75% of its activity. The S.A. has an activity curve with a broad optimal zone between pH 4.0 and 5.75 while the D.A. has an optimal point at pH 5.5-6.0. Osmometric measurements during the hydrolysis of starch with D.A. show that the starch molecules are split into two or more dextrin molecules which are then split into smaller molecules which are again split up with maltose as the endproduct. With S.A., however, maltose is formed at the very beginning: the starch molecule is split into one or more molecules of maltose and a remainder, dextrin, which in turn is split into maltose and dextrin, etc. Polarimetric measurements made during starch hydrolysis according to the method of R. Kuhn show that the S.A. hydrolyzes the starch with the formation of [beta] maltose while during the hydrolysis with D.A. [alpha] maltose is formed. The D.A. is therefore an [alpha] amylase and the S.A. a [beta] amylase.