1. Experiments are described in which were studied the effect of flowers of sulphur on the growth of young white rat maintained on two types of basal diets, one a modification of the low protein diet of Osborne and Mendel and the other a ration complete in all respects from a nutritional standpoint of this species of animal.
2. Sulphur, when added to the amount of 0.8 per cent. to the low protein diet which was also low in cystine and “food sulphur”, caused a marked retardation of the rate of growth but no deaths during an experimental period of 60 days.
3. The toxicity of sulphur when added to a well-balanced ration in concentrations varying from 0.1 to 3.5 per cent. was, comparatively speaking, rather low. A comparison of the rate of growth of young rats by the paired-feeding method of Mitchell and Beadles showed that the number of weeks during which the control rats gained more in weight than their litter mates on the sulphur rations, is reasonable near 50 per cent., which indicates that the different treatments show no significant difference amongst themselves.
4. The solution of the problem as to why certain rations show greater antitoxic effect to sulphur poisoning than others should probably be looked for in the difference in their protein and “food sulphur” contents. The results to date seem to show that rations, complete in all respects for growth with optimum protein and easily available “food sulphur” contents, possess greater antitoxic effect to sulphur poisoning than rations that are low in these constituents.
5. Large amounts of flowers of sulphur can be given to animals (rats) without marked deleterious effects on their rate of growth when optimum amounts for growth of a well-balanced ration (stock) is given at the same time.