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Crane, Hatefi, Lester and Widmer1,2have shown that coenzyme Q is reduced by mitochondria or derivative particles like electron-transporting particles, or succinic dehydrogenase complex, and that this reaction is sensitive to antimycin A. We have now succeeded in reducing coenzyme Q with a soluble preparation of succinic acid dehydrogenase, and this reaction was not sensitive to antimycin A.

Piles of vegetational clippings made by Sigmodon hispidus in a remnant grassland area were collected and analyzed for vegetational composition, dry weight, and caloric content. Population densities of S. hispidus were estimated monthly and correlated with the number of clipped piles of vegetation collected each month. During the 1-year study period, Sigmodon clipped 315.1 kilograms of vegetation on the 4.85-hectare study area. This amounted to 136.1 × 104 kilocalories. Grasses (mainly Andropogon gerardi, A. scoparius, and Bouteloua curtipendula) accounted for 54 per cent of the vegetation clipped, Ambrosia psilostachya and Kochia scoparia 40 per cent, and Helianthus annum 6 per cent. Seventy-two per cent of the clippings occurred from September to November. The amount of clipped material per rat per month varied from zero in May to 1.3 kilograms in October. The amount of material clipped may not be dependent solely on the density or activity of S. hispidus, but possibly also on the condition of the vegetation. Of the net primary production in this area during the study period, 0.4 per cent was clipped by S. hispidus.

IT has been pointed out to us that our recent communication under this title1could be misunderstood as a claim of having first shown the insensitivity to antimycin A of reduction of ubiquinone. The credit of this observation belongs to Drs. A. M. Pumphrey and E. R. Redfearn2. The purpose of our communication was to show that this reduction could be obtained with a non-particulate soluble preparation, simpler than those which have mostly been used hitherto.