Error in glasshouse experiments

Summary The proportions of plot variances that are assigned to error in glasshouse experiments at Bayfordbury are examined to determine the number of replications required per treatment.The relationship between average percentage standard error and weight of tomatoes picked by the end of a week is examined to discover which is the most suitable week on which to base an estimation of early crop. This was found to be the cumulative weight of fruit picked by the end of the fourth week after picking commenced.The gradients apparent on glasshouse benches and in crop houses were studied so that the experimental designs used could take these into account. Randomised blocks are suitable for experiments with small pots and germinating seeds on the benches. Where practicable a Latin Square design would be most suitable for cropping experiments with tomatoes grown in the beds, especially in the unequal span house orientated east and west, at Bayfordbury.     

A DEVICE TO ASSIST IN ESTIMATING SMALL NUMBERS OF BACTERIA IN LIQUIDS

SUMMARY: An apparatus is described which assists the determination of small numbers of micro-organisms in liquids by enabling volumetric samples to be taken without risk of aerial contamination. Three sets of 5 containers of 5, 50 and 500 ml are mounted in a common vessel, and are filled as part of the sampling process, and one 2,500 ml sample is contained in an inter-connected flask. The number of containers showing bacterial growth is used in conjunction with probability tables, to estimate the number of bacteria in the liquid.