We describe a new automated dye-binding method for serum albumin determination with bromcresol purple (BCP) that has several advantages over an existing bromcresol green (BCG) method. The continuous-flow method is sensitive, linear, and precise, with negligible sample interaction at an analytical rate of 60 samples per hour. Unlike BCG, BCP did not react with an albumin-free serum globulin preparation or pure human transferrin solutions. Reaction with serum was instantaneous; in contrast, BCG exhibits a slow nonspecific reaction with some specimens. The specificity of BCP was demonstrated by good agreement with results of "rocket" immunoelectrophoresis (EIA) where y(BCP) = 0.95X(EIA) + 1.72. The BCG method overestimated serum albumin concentration where y(BCG) = 1.01X(EIA) + 6.77. Precipitation, which affects the BCG method, was not observed with BCP. Blank corrections were negligible, salicylate did not interfere, and bilirubin affected the method only if present in very high concentration. The method offers a solution to the poor accuracy of existing BCG methods while retaining many of their desirable features.

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The growth requirements of a strain of Schizosaccharomyces octosporus were studied by auxanographic and tube tests. The organism grows satisfactorily on a glucose + mineral salts medium containing asparagine and ammonium sulphate, provided also that inositol, pantothenic acid, nicotinic acid, biotin, histidine, methionine and adenine are added. Coniplex interactions between adenine and guanine were found, and for this reason 8. octosporus cannot be regarded as a suitable test organism for the assay of adenine.The present investigation arose from studies still in progress of the. inositol requirements of a number of yeasts. Twelve strains were examined, and growth of eleven of them was satisfactory when inositol or yeast extract was added to a defined medium containing glucose + mineral salts, ammonium sulphate, casein hydrolysate and B vitamins. The exception was S . octosporus which failed to grow in absence or presence of inositol. Further investigations showed that S . octosporus required adenine, not hitherto reported as an essential metabolite for yeasts, and its growth requirements were therefore studied in more detail. METHODSTube tests. The usual procedure for microbiological assay was followed, but in place of bacteriological tubes, flat-bottomed tubes (Samco), 4 x 9 in., were used.Tubes were selected so that the internal diameter was within the limits 1-66 and 1-72 cm. The tubes, containing 6 ml. of test medium and covered with loosely fitting glass caps, were sterilized for 10 min. a t 10 lb. pressure. After inoculation, they were incubated in a vertical position at 25" in a water-bath.Estimation of amount of yeast growth. The tubes were fitted into a black wooden container open a t opposite sides which held them in the optical beam of the Spekker absorptiometer, in the place normally occupied by the glass cells. Thus turbidity readings could be taken from the same tube a t intervals during the growth of the organism, without exposing the contents to contamination.Test organism and inoculum. The test organism, carried on malt agar slopes, was subcultured weekly or more frequently as required. In the preparation of the inoculum a loopful of a 24 hr. culture was suspended in 6 ml. of basal medium to give a turbidity in the tubes reading between 0-15 and 0.25 in the Spekker (i.e. approximately 0.2-0-4 mg. dry weight yeast/6 ml.

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