There is now a great deal of interest in group 13, 14, and 15 elements in low coordination states.1 Since 1981, several new compounds of the type M=M/ (M and M': group 13, 14, and 15 elements) withbonds have been reported. In organogermanium chemistry, the first stable derivatives with a sp2-hybridized germanium have only been prepared very recently: they are the digermenes R2Ge=GeR22 (R = bis(trimethylsilvl) methyl,23 2,6-dimethylphenyl,2b 2,6-diethylphenyl2c), the germaphosphene

Volume 37, no. 2, p. 148, Table 3: Growth at 40°C should read " + " for P. avenue and P. cattleyae.

The addition of iron to an iron-deficient medium markedly enhanced the growth of "Pseudomonas plantarii" and the production of red crystals. However, it markedly reduced the amount of dissolved tropolone, a product of the bacterium and an iron chelator, and the production of an iron-regulated protein (78 kilodaltons). The red crystal was complex, composed of tropolone and iron, the ratio being 3:1. "Pseudomonas plantarii," recently reported to be the causal agent for seedling blight of rice grown in nursery boxes, produces tropolone (Fig. 1)(4, 5). The term tropolone was proposed in 1945 for the seven-member ring structure in colchicine and mold metabolite stipitatic acid (7, 8). In 1980, tropolone itself was found to be produced in nature; i.e., it

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