Imaginary Drug Effects.--Drug effects may be produced through the imagination. Physicians know that when patients are persuaded that certain effects are to be expected from a particular medicine, the effects may follow all the same in sensitive, imaginative people, if that medicine is replaced by some inert compound. Many a physician who has used bread pills or other placebos to replace a drug that he did not want the patient to acquire a habit for, has thus been able to allow good effects to go on without interruption, where the stoppage of medicine had previously interfered with the continuance of the good habit that had been formed. Very few physicians have not seen the effect of a hypodermic of pure water when a hypodermic of morphine is demanded, and when the patient would not sleep without having the hypodermic injection. Sleeping powders of various kinds can sometimes with distinct advantage be replaced by inert materials, because the patient's mind is fixed upon the idea of sleep coming after a certain time and they, in consequence, compose themselves to rest. The Nerves and Tissues.--Cases occur where disturbances of vitality are noted as a consequence of nervous affections, though no gross lesion of the nervous system is demonstrated. Certain nervous people suffer from ulcerative conditions of their hands, and it is evident that in some the nervous impulses {89} that would ordinarily keep the skin surface in good, healthy condition are insufficient. Some people who use a typewriter have no difficulty at all with the ends of their fingers, while others are subject even to loss of skin or ulcerative conditions that make it almost impossible for them to go on with their work. In some this is true in the winter, in others in the summer. There are a number of skin conditions which are due to nervous factors and these evidently point to the influence of the central nervous system in keeping the forces of our body in such health, and resistive vitality, as will enable us to carry on whatever work we may wish to. This is, of course, a very individual matter. Some people chap very easily, some suffer from chilblains, or are frost-bitten even on slight exposure, and these peculiarities are evidently dependent on the intensity of the nervous impulses as well as the tone of the circulation, which itself depends on the nerves to a great extent.