Vol. I 2 Plant and microbial nitrogen in the rumen 429 4. The diaminopimelic acid present in the microbial fraction has also been used to differentiate the bacterial nitrogen from the protozoal nitrogen. The authors wish to thank Miss M. C. Dawbarn and her colleagues for carrying out assays of vitamin B" activity. The metabolism of nitrogen, calcium and phosphorus in undernourished children 4.* The effect of replacing rice in the diet by tapioca macaroni on the metabolism of nitrogen, calcium and phosphorus