WORK in this Institute on the enzymatic breakdown of starch has included above all the qualitative and quantitative determination of products resulting from this breakdown1. We have observed that in every case fructose occurred beside the glucose derivatives already in the barley malt extract2. The presence of glucose may be attributed to the activity of the amylo-glucosidase enzyme of the barley malt. Among the glucose derivatives maltose is produced by the activity of the well-known β-amylase. The oligosaccharides, from which we succeeded in identifying altogether eight members in two homologous series, beginning with maltotriose and finishing with malto-octaose, were produced by the activity of the amylase. Besides the amylolytic enzymes, there must also be a glucose-isomerase enzyme in action, and it must be its effect which results in the appearance of fructose.