Metal pollution in the river Godavari in India, due to discharges of liquid wastes from a paper mill, has been studied for a period of two years. At the discharge point and 1 km from the point of discharge, iron, manganese, and zinc were recorded in high concentrations, whereas cadmium and chromium were observed in low concentrations. No metal was in detectable concentration in water before the river receives the effluents. A considerable drop in pH values and an appreciable increase in organic matter, hardness, and calcium levels were noticed after entry of wastes. Diatoms were more diversified in fresh water, whereas cyanobacteria were more prevalent both qualitatively and quantitatively at the polluted stations. Mathematical equations involving heavy metals and physicochemical factors were drawn for better understanding of the distribution of algae.

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have added to our knowledge of river ecology . The majority of these investigators, however, have not taken into great detail the chemical composition of water and their observations did not continue for longer periods of time . Apart from this very few have attempted to study the benthic algae of rivers . The studies of BISWAS (1942-43) and GHOUSUDDIN (1934) deal mainly with the floristic distribution of algae in Hooghly and Moosi rivers .Although a number of rivers studied have contributed very important data in the field of ecology, still the overall picture which looms behind the inter-relationships of various physico-chemical factors in river waters correlated with the periodicity of different groups of algae is somewhat hazy. This may possibly be due to the lack of sufficient data collected over a longer period of time. Taking into consideration all these factors, the present study was undertaken with a hope that it might help in elucidating certain insufficiently

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developed in Part I11 (J., 1960, 3117) has been extended to the synthesis of flavani and their derivatives from a series of polyhydroxyphenols. From some a number of a-and y-pyronoflavans have been prepared.IN reviewing possible routes for the synthesis of dracorubin-type compounds we were attracted by the idea of employing a residue of type (I), containing the flavan system already formed, rather than to attempt the construction of this unit on to a flavylium compound, more especially because of the experimental limitations encountered in the synthesis of the flavan system (Part 111, J., 1950, 3117). As a preliminary to exploring this route to the dracorubin system the general procedure developed in Part I11 (Zoc. cit.) has been extended to the svnthesis of a series of flavans from resorcinol, orcinol, quinol, hydroxyquinol, and keto-derivatives it (111), and (IV). R phloroglucinil, and pyrogallol. Further, from some of the formylhas been possible to obtain, e.g., cc-and y-pyronoflavans, types (11),In these studies there emerged several experimental features of general interest which may be noted. (a) Most parent flavans are extremely dficult to crystallise and several of the hydroxy-compounds are readily susceptible to aerial oxidation. (b) The flavan oxygen system is sensitive to acidic reagents above room temperature and attempts to demethylate O-methylflavans by the standard methods are uniformly unsuccessful. Further, whilst, e.g., 8-formyl-7-hydroxyflavan (I ; R = CHO) readily reacted with acetophenone in ethereal hydrogen chloride, the resulting flavylium salt was resinous and could not be purified. (c) With chromic anhydride O-methylflavans furnish low yields of the corresponding flavanones, thus providing a method of detecting the flavan system. EXPERIMENTAL 7-HydroxyfEavan (I ; R = H).-A solution of 7-hydroxyflavanone (Ellison, J. , 1927, 1722) ( 1 g.) in acetic acid (40 ml.), containing concentrated hydrochloric acid ( 5 ml.), was reduced with zinc amalgam (from 10 g . of zinc dust) at room temperature and 24 hr. later the solution was decanted and diluted with water. Purification of the resulting precipitate from light petroleum (b. p. 6O--SO0), containing a small amount of methanol, yielded 7-hydroxyfavan (0.7 g.) in prisms, m. p. 71", readily soluble in 2~-aqueous sodium hydroxide and having a negative ferric reaction (Found : C, 79.6; H, 6.3. Cl5Hl4O2 requires C, 79.6; H, 6.2%). 7-Hydroxy-8-rnetlzyZ~7avan (I ; R = Me) .-(a) Prepared by Gattermann's method from 7-hydroxyflavan (1 g.), hydrogen cyanide ( 5 ml.), and zinc chloride (0.5 g.) in ethereal hydrogen *