New or Interesting Myxophyceae from Missouri

Abstract

A few new or otherwise interesting blue-green algae have appeared in my collections from time to time during the past five years. The recent discovery of a number of unidentified specimens in the Herbarium of the Missouri Botanical Garden, collected by Dr. WILLIAM TRELEASE, brought to light several species in this group which have not previously appeared in the lists of Missouri algae (2, 3, 5, 6). Scytonema alarm (Carm.) Borzi has lately been recorded from Shannon Co. by SHARP (8). The Myxophyceae are a difficult group, not only because of their few and minute taxonomic characters, but also because these characters may be easily changed by the mode of preservation. Formalin and other fixing agents produce granules and distortions of shape not found in living material. Dried algae are not always satisfactory for study. Living material cannot always be conveniently examined, especially on collecting trips of more than a day's duration, since deterioration sets in shortly after collection. The most satisfactory method of fixing which I have found' is with a 3-5% aqueous solution of commercial formalin (40o formaldehyde). Plenty of liquid should be used so that the killing agent may penetrate throughout the mass as quickly as possible. Most of the observations on fixed material have been supplemented by the examination of living material. BOYE PETERSEN (i) and GEITLER (4) have discussed the relative merits of diagnostic characters among the blue-green algae, and I have here placed most emphasis upon size and shape of cells, especially those at the ends of the trichomes, and the reaction of chlorzinc-iodine upon the sheaths. Chlor-zinc-iodine' solution is prepared