A variant of human lactate dehydrogenase is described. The occurrence of lactate dehydrogenase-1, -2, -3, and -4 as five, four, three, and two components, respectively, is interpreted as supporting the hypothesis that LDH isozymes are tetramers formed from various combinations of two types of subunits.

The trail-marking substance of Atta texana (Buckley) is formed in the true poison gland and deposited by the sting. This attractant is initially produced by teneral workers. The substance obtained from mature, large workers is the most potent.Trail-following behavior is highly de?veloped in the Texas leaf-cutting ant, Atta texana (Buckley).This ant marks its trail with a substance that is highly persistent, stable, and perceptible to ants even when it is in minute quantities. It is produced by the true poison gland and deposited by the sting, which is not used for stinging; thus its defense mechanism is used for purposes of communication.

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Ultrafiltrates of human myoglobin from 200 individuals were examined by starch-gel electrophoresis. Only two variants, Mb Aberdeen and Mb Annapolis , of the commonly occurring myoglobin Mb + were encountered. Each variant is apparently inherited as an autosomal codominant. Heterozygotes for either mutation lack apparent muscular disease. Combined electrophoresis and chromatography of Mb Annapolis indicate a loss of arginine at a position near the C-terminal portion of the molecule.

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