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This work was performed in an a t tempt to establish, in part, the biochemical nature of a microbody-like structure of the filamentous green alga, Klebsormidium. There is only one such structure in each celt. I t is usualIy lenticular or discoid and invariably occurs between, and appressed to, the chloroplast and nucleus. The microbody-like organelle divides during mitosis and the division of the chloroplast (5). Another objective was to compare the nature of a microbody of a filamentous alga with the microbodies already described for some unicellular algae and for vascular plants. Microbodies or microbody-like structures, as determined by structural features, have been observed in the unicellular algae, ChloreIla (8), P@'tomella and Chlorogonzum (9), and Euglena (11). These structures have a single limiting membrane and a uniform granular matrix. Microbody enzymes are reported from in vitro studies of EugIena (10, 12), and Polytomella and Chlorogomum (9). However, techniques for the cytochemical localization of catalase were negative on EugIena, Polytomella, and Chlo~ogonium, and no a t tempt of eytochemical localization was reported for Chlorella. The explanation for the lack of, or negligible activity of, catalase in Euglena has been discussed by Graves et al. (11). In Euglena, and other algae grown on acetate or ethanol in the dark, the production of acetyt CoA originates from the 2-carbon substrates rather than from fatty acid metabolism as occurs in /3-oxidation in vascular plants, and very litde hydrogen peroxide is produced. Also, the glycolate-oxidizing enzyme in several unicellular algae is a dehydrogenase, not an oxidase as in vascular plants (2, 13, 15), hence the absence of a hydrogen peroxade-producing system. Tolber t (18) suggests that the different pathway of glycolate metabohsm is a major difference between vascular plants and unicellular algae. Possible exceptions to Tolbert 's suggestion are the reports of glycolate oxidase in a Chlorella mutant (17), and Scenedesmu~ and Ankzstrodesmus (14). However, the reports on ChlorelIa and Scenedesmus seem to be contradictory (14, 15). The recent negative results of attempts of cytochemical localization of catalase support Nelson and Tolbert 's (I5) report of the absence of glycolate oxldase in m a n y unicellular algae.

CYTOCHEMICAL DEMONSTRATION OF A SINGLE PEROXISOME IN A FILAMENTOUS GREEN ALGA