81 abnormality and the lack of the factor for any vitamin other than aneurin (vitamin B1). We have now at last a final proof that ancurin pyrophosphate is the actual factor missing in the avitaniinous brain (Banga, Ochoa and Peters, 1839). It has taken long t o reach this.Always the pliysiology will take the longest. Thc fact is that chemistry and hiochcmistry have rushed ahead lately and we must not be disappointed if the true nutritional wet+ takes rather longer to do, bccause it involves physiology. Today we shall be discussing our subject from the dual aspccts of pure biochemistry and of nutrition.