The effect of dietary amino acids on the growth ofHymenolepis diminuta

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Abstract
The effect of an amino acid imbalance in the diet on the growth ofHymenolepis diminutain rats was reinvestigated. The claims of earlier workers that growth of the tapeworm is retarded was not substantiated.The size frequency distribution of 575, 13-day-oldH. diminutarecovered from 9- and 10-worm infections was determined, to reveal the shape of the distribution and total variance. The total variance in worm weights was analysed to determine the amount attributable to variance ‘between rats’ (comparison of the mean weight of the worms recovered from rats) and variance between worms within individual rats. ‘Between rats’ variance was found to account for > 80% of the total variance.Assuming variance equal to that in the experiments described, the degree to which experiments can determine a difference in effect between two diets on the growth of tapeworms is analysed, and the degree to which this is altered by increasing the number of rats in dietary groups and/or decreasing the ‘between rats’ variance is estimated.The suitability of various procedures for host dietary experiments on tapeworms is discussed; these include the duration of the experiment, feeding regime, age of worm and the relative advantages of weighing worms singly or in groups.We gratefully acknowledge the technical help we have received from Miss Patricia Grant and Mr Jack Keys. Our thanks are also due to Mr Robert Elton of the University of Glasgow Statistics Department who has advised us on statistical procedures and calculated Table 6.