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The application of the catalysed oxidation of Bromopyrogallol Red by potassium per- sulphate for silver determination is discussed. In aqueous solution silver concentrations of 0.5- 1 mug/ml can be determined and 1- 13 ng/ml in the presence of 1, 10-phenanthroline as activator. In combination with solvent extraction, catalytic determination of the extracted silver is possible even in presence of 200 mug of iron(III), cobalt(II) and palladium(II). By means of an automatic variant of the simultaneous comparison method a more sensitive determination (0.2-20 ng/ml) was achieved.

The correlations found between yield and content of several varieties of alfalfa show that selection for green matter only does not result in the deterioration of fodder quality. Green matter variability has more influence on the yield of dry matter, crude protein, and phosphoric acid than does the corresponding content; only the yield of carotene depends less on the green matter yield than on the carotene content.Variability in content decreases from carotene to phosphoric acid to crude protein, which makes the increase of carotene content easiest, that of crude protein hardest to achieve.

In an examination of the susceptibility of 27 fodder grass varieties cultivated in the GDR to 14 races of barley mildew, 9 races of wheat mildew and 1 population of rye mildew no infections were obtained. Since the races used represented the whole range of pathogenicity of the known races of cereal mildew, it may be assumed that under natural conditions cereal mildew does not cause any infection in the examined varieties of forage grasses.

Positive selection of alfalfa shoots from a drilled stock showed a negative effect in the progeny tested under drilling conditions. The selection of largest plants in an early stage showed the same result. It could be proven in both cases that material from self-fertilization was preferred. This results in inbreeding depression. Self-fertilization caused a decrease in the number of seeds per pod. This, in turn, allowed some seeds to become larger and young plants more robust than with natural cross-pollination.

In the described experiments the interaction of 460 grass species with a mildew population obtained from Dactylis glomerata L. 'Motterwitzer' was examined. 420 species remained free of symptoms, while 40 species were susceptible. The most susceptible ones were Dactylis aschersoniana Graebner, Dactylis glomerata L., Dactylis glomerata spp. aschersoniana (Graebn.) Thell., and Dactylis polygama Horvat, but all showed differences in their behaviour. The unexpectedly low susceptibility of Dactylis woronowii Ovcz. should be examined again. Three grass species Bouteloua hirsuta Lag., Danthonia provinzialis DC., and Sesleria latifolia (Adam) Degen were also highly susceptible to cocksfoot mildew, while on wild grasses of the species Agropyron, Bromus, Festuca, Mibora, Poa, and Sesleria only few symptoms could be seen. Among cereals only barley could be infected by cocksfoot mildew. Not only in the wild form of Dactylis glomerata L. but also in the cultivated variety 'Motterwitzer', above 10% were found to be free from infection. Therefore the breeding of resistant varieties of Dactylis glomerata L. seems to be feasible.

Yeast phosphofructokinase exists in several enzymically active, interconvertible forms with molecular weights of 180,000, 370,000, 570,000 and 750,000. With disc-electrophoresis catalytically active aggregation products with molecular weights of more than one million can be detected.In alkaline media fragmentation of phosphofructokinase occurs, leading to a variety of catalytically inactive products. These seem to be oligomers of subunits with 60,000 daltons. A model of the complex subunit structure of yeast phosphofructokinase is suggested. The various catalytically active forms of the enzyme are considered as polymers of 180,000 monomers, which themselves are enzymatically active and which are composed of three 60,000 subunits.

A new method for molecular weight determination using polyacrylamidegel electrophoresis in a linear gel-concentration-gradient (3-20 degrees ) is described. Plotting the log of molecular weights of several standard proteins against distance of migration or against 3 log of rate of n-dgration reveal linear relationships in ranges of 50.000 - 200.000 or 100.000 - 400.000 Daltons respectively. On this basis, a simple method for molecular weight determination of proteins (accuracy +/- 5 degrees ) has been devised. The method can also be applied for an individual protein in protein mixtures using specific staining procedures.

In comparison with self-pollination of alfalfa flowers fertility increased with geitonogamy to intraclonal pollination; the number of seeds per pod and seed size were also favourably influenced. Plasma differentiation may be the reason. Methodical aspects of genetic and breeding studies are discussed.

Bovine liver catalase is separated into several distinct bands by electrophoresis in a linear concentration gradient of polyacrylamide. Apparently, disc electrophoresis under these conditions leads to a series of enzymatic active forms of catalase. Their molecular weights are: 248,000; 295,000; 368,000; 486,000; 705,000 respectively. Density gradient centrifugation separates catalase into two components with molecular weights of 252,000 and 316,000. The observed differences in molecular weight distribution between gel-electrophoresis and density gradient centrifugation are discussed.