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SUMMARY Proteins of whole cell extracts from 16 Chlorococcum species and 3 Tetracystis species (formerly Chlorococcum) were analyzed for isozymes of nonspecific α‐esterases, leucine aminopeptidase, and malate dehydrogenase using starch gel electrophoresis. Each species could be identified by the banding patterns. Chlorococcum species are heterogenous regarding the presence, number, electrophoretic mobility, concentration, and distribution of isozymes. The data are discussed in relation to current knowledge of each species. Taxonomic applications of algal isozymes are considered.

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The growth‐related inhibitory effects of mercuric chloride (MC), methylmercuric chloride (MMC) and phenylmercuric acetate (PMA) (each at 1, 10, 10,2 103 ppb) were measured in Anabaena flos‐aquae (Lyng.) Bréb. and Anacystis nidulans (Richt.) Drouet & Daily. Optical density changes of control cultures compared against those of experimental cultures showed that MC was the least inhibitory of the compounds. MMC. was the most inhibitory, producing statistically significant inhibition at a concentration as low as I ppb in Anabaena. PMA was more inhibitory than MC but less than MMC. Effects caused by the mercury compounds included bleaching of individual cells, cell size changes and destruction of whole cells; the degree and extent of these effects depended on the compound and its concentration in the nutrient medium. The high sensitivities of the algae tested suggested the possibility of using them as test organisms in bioassays for mercury.

Dormant seed and organs of 0‐, 1‐, 2‐, 5‐, 8‐, 11‐, and 14‐day‐old plants of Arachis hypogaea L. were homogenized in phosphate buffer and the lipid‐free extracts analyzed for benzidine and pyrogallol peroxidases using starch‐gel electrophoresis. On a wet weight basis, one weak band of benzidine peroxidase activity was detected in dormant cotyledons and three bands in 1‐day cotyledons. In 5‐day tissue, activity had increased significantly; at 14 days, the number of bands had decreased but staining intensity was maintained. In the extract from dormant axis, a single cathodic site of benzidine peroxidase activity was observed; however, on day two there was a marked increase in the number of bands and intensity of reaction in epicotyl and hypocotylradicle tissues. By day 14, the number and density of bands had decreased noticeably in the epicotyl and hypocotyl. Extracts from 14‐day roots exhibited more sites of reaction and greater intensity of staining of benzidine peroxidase than at five days of growth. Localized areas of activity at Rf ‐0.44 and ‐0.52 were present in extracts of all four organs when either benzidine or pyrogallol was used as the hydrogen donor. Although marked similarity existed between banding patterns of organs, qualitative and quantitative ontogenetic differences in peroxidases were apparent.