Most of the general excitant influences, though they may in a greater or less degree affect the whole system, are characterized by having a preferable tendency to some one of the subordinate systems rather than to another; and hence the stimulants belonging to this section are divided into the arterial, the cerebral, and the nervous, according as they exhibit a tendency to excite more especially the circulation, the brain, or the nervous tissue generally. To this rule, however, there is one striking exception. Heat is a vital stimulus essential to the support of every function in its normal state, and capable, therefore, when operating in excess, of producing over-excitement in all parts of the body. It is a universal stimulant, and is capable of being remedially employed as such with very great advantage. The consideration of it as a remedy falls within the scope of this work, and, in relation to its stimulant powers, belongs especially to the present section. Having, however, other therapeutic properties, it will, in reference to these, be treated of in connection with the several classes to which it may belong, as the diaphoretics, rubefacients, epispastics, and escharotics. The following observations apply only to its properties and uses as a diffusible stimulant Electricity is another diffusible stimulant, which, though employed more especially in reference to its action on the nervous system, is really universal in its influence, and can be brought to bear, as a rapid and powerful excitant, upon any one of the systems or organs of the body. This, therefore, must be considered as belonging to the present division of remedies, and will be treated of after heat