Abstract. Alcohols induce mating-structure activation inChlamydomonas eugametos gametes. From the effect of ethanol on the 32p-labelling of polyphosphoinositides, we conclude that the synthesis of these lipids is stimulated. Biologically inactive concentrations of ethanol (<6%) had no effect on synthesis, but 6-8% ethanol stimulated synthesis for upto 60 min. The 32p incorporated into polyphosphoinositides and phosphatidic acid during ethanol treatment was readily chased out when 1 mM unlabelled Na3PO4 was added. Using a binding assay for inositol 1,4,5-trisphosphate, we show that the production of this phospholipid constituent is dramatically increased after ethanol treatment. This effect, coupled to a rise in intracellular calcium concentration, could explain gamete activation. The significance of these results in explaining other ethanol-induced phenomena in algae is discussed.

SUMMARYOne hundred and eighteen different strains of Proteus vulgaris were investigated for bacteriocinogeny. These and an additional 44 strains of P.vulgaris were used as indicators. Sixty-seven of the strains had a nontransmissible killing effect on one or more of the indicator organisms and 3o of these 67 bacteriocins with different spectra of activity were further investigated. Individual bacteriocins killed from 5 to 87 of the P. vulgaris indicators and a number of 44 different P. mirabilis strains but had no action on strains of other species of the family Enterobacteriaeeae. Broth cultures of bacteriocinogenic strains are inducible by ultraviolet fight and yield bacteriocin titres of about I/IOO. Activity is sedimentable by high-speed centrifugation. Electron microscopy of all 3o preparations revealed similar phage-tail-like structures with a contractile sheath round a hollow core. The structures consisted of protein and did not contain DNA. The particles resembled some pyocins and also the tail of a P. vulgaris transducing phage. In z preparations a few phage-like particles resembling other Proteus phages were also seen. Bacteriocin activity was always associated with uncontracted sheaths, and triggered tails did not adsorb to susceptible organisms. We conclude that the tail-like structures are the products of defective lysogeny. The high incidence of the latter state may be accounted for by the selection of genes favourable to the host which were originally acquired through transduction by lysogenization or lysogenic conversion.

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SUMRlARYTwelve phages isolated from sewage and active on lactobacilli were examined by electron microscopy with a negative-staining technique, Those phages active on Lactobacillus fermenti (heterofermentative) possess icosahedral heads and sheathed tails which end in base-plates and pins. Those phages active on Lactobacillus casei (homofermentative) differ in that their heads are octahedral or icosahedral and they possess collars. The overall length of all the phages is similar and their base-plates remain attached to the sheaths when these contract. No tail fibres were seen. A temperate Lactobacillus fermenti phage was also examined. It has a small hexagonal head and a long unsheathed tail which ends in a starshaped structure.

The morphology of 28 bacteriophages active on members of the ProteusProvidence group of organisms was examined by a negative staining technique. Examples of the 'T-even', T 3 and P22 morphologies were encountered as well as phages with non-contractile cross-striated tails resembling a group of coliphages. Others resemble staphylococcal and pseudomonas phages. Two phages (9, 7479) with octahedral capsids were encountered. A temperate Proteus mirabilis phage (12/57) and a temperate P . morganii phage (10041/2815) differ from phage P 22 in that they possess collars. A P. rettgeri phage (7480 b) is unique in that it possesses a head with a regular hexagonal outline, a collar and a non-contractile tail while a Providence phage (9266) is believed to be the largest phage active on Gram-negative bacteria.