1. The influence of diets having different protein values on the schistosomicidal effect of Ambilhar has been investigated in mice.2. Mice placed on these diets throughout the period of infection and then treated, reached differently. Low protein diets produced fewer and smaller worms which were more susceptible to the drug.3. Mice maintained on an adequate diet were shifted to diets of varying protein values a few days before treatment. In these, drug treatment was more satisfactory in animals fed the high protein regimen.4. Female worms were more affected by drug treatment than the males.

1. The susceptibility of two strains of rats, namely London-hooded and Wistar, to infection with S. mansoni has been investigated2. Although equal numbers of cercariae penetrated the skin in both strains, recovery of worms was always higher from the London-hooded strain irrespective of the dosage level.3. In both strains there was a significant relationship between body weight at time of infection and number of worms recovered. The correlation was a negative one, indicating that lighter (younger) rats were more susceptible than heavier (older) rats.4. A rapid rate of elimination of infection was demonstrated in London-hooded rats between the 4th and 8th week after infection.