During the spring of this year, my friend Lieutenant Crocket, R.A.M.C., obtained, through the kindness of Dr. Noguchi, a small supply of luetin, and with this he carried out a series of tests, to which he was anxious to add some observations on its use in mental cases. By permission of Dr. G. M. Robertson he was able to examine a series of cases in Morningside Asylum, and I was fortunate in being asked to co-operate with him. Owing to our small supply of luetin, the number of tests done was necessarily limited, and we intended carrying our observations further when Crocket was called away to duty. Only a short time ago the sad news of his death in action was received, and it is largely on this account that I venture to place on record so small a number of observations.