The study of the relationship of the psychical and the endocrine mechanisms is made more difficult by the fact that the body does not react by separate systems, but as a coherent interlocking piece of machinery. Not only does the mind react on the glands and vice versa, but each gland reacts on the others to some extent. If follows therefore that one syndrome can be produced by two or more glands or by the mind and one gland. An example of the first is the adiposity, sexual dystrophy and hirsutism which make adrenal and pituitary syndromes so confusing, and of the second the difficulty in differentiating anxiety states from thyroid disease.