1. Lactose had an unique effect on the nutrition of rats. None of the lactosefed rats developed dermatitis, but cataract. The animals continued to grow even on the entire B₂ deficiency. Vitamin B₆, flavin or filtrate factor separately administered did not give any appreciable improvement on either growth or cataract. When all three factors, B₆, flavin, and filtrate factor, were supplied, a definite effect on growth was produced and slower development of cataract was brought about.
2. The rats fed on the corn-starch diet failed to grow and developed alopecia unless flavin and filtrate factor were supplied. Vitamin B₆ had little effect on improvement of the growth rate. This factor appeared to be present in the starch. When fed on the corn-starch diet containing 5% cane molasses, the rats maintained themselves at 70g for a prolonged period and developed severe alopecia and sore eyes, but no cataract.
3. When sucrose was used as the basal carbohydrate, earlier and severer development of dermatitis and growth failure occurred unless vitamin B₆, flavin and filtrate factor were supplied. No cataract appeared on this diet. Apparently sucrose is completely free from all three factors and is therefore the carbohydrate of choice for the study of the vitamin B₂ deficiency.

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