The present paper records an attempt to investigate certain metabolic phases of muscular and glandular activity, and their relationship to the secondary changes which result in the muscle and the gland. By the terms “muscle” and “gland” we mean, not the muscle fibre and the gland cell, but the complex of tissues, contractile, vascular, lymphatic, etc., which form a muscle in the gross sense of the word, and the corresponding structures which form a gland. Either muscular contraction or salivary secretion is accompanied by changes, not only in the contracting or secreting cell, but in the various accessory structures. Our endeavour was to make some analysis of these changes, and of their relation to one another, further than has hitherto been done. Our method differs from most of those which have been used by previous workers in that we desired to subject our tissues to much longer periods of exercise than others have done. In some crude way we wished to simulate the conditions which obtain when actual exercise is taken by the body. Thus, in our experiments on muscle, we exercised the muscle rhythmically for 15 minutes, in those on gland we gave sufficient pilocarpine to produce a prolonged secretion. In this way we hoped to obtain effects in the metabolism of the muscle, as well as secondary effects in the blood vessels, lymph flow, etc., which we might fairly compare with those which take place in the body.