I consider, then, that Quina is not in the first instance a Neurotic medicine; and for the following reasons. The action of other nerve-medicines is distinguished by the following signs. It is quick, and very rapidly follows the administration of a substance. It is transient, and does not endure. It requires no particular state, but takes place in health: thus Alcohol stimulates and intoxicates both healthy and sickly, and Digitalis would subdue a Hercules. Most Neurotics are capable of acting without entry into the blood at large; mere contact with the nerves, as when they are applied externally, being sufficient for their action on those nerves. Again, Neurotics are chiefly used in cases in which the nervous system is unusually excited or depressed, and are of no permanent efficacy in diseases depending on blood-disorder. The action of Hæmatics is of an opposite kind. Now is the primary action of Tonics distinguished by the above signs? Are they quick and sudden in action? Is their effect transitory? Is it evidenced in health as well as in disease? Do they act on the superficial nerves, when applied to them? In each case the answer must be a negative. In all of these particulars the operation of vegetable bitters differs from that of Neurotics, and coincides with that of Hæmatic medicines. It appears that their action on the nervous and muscular systems is secondary. They could hardly in either case effect any permanent improvement without first acting on the blood, if we may argue from known analogies. For Neurotics and Astringents, which operate directly on these two systems, are alike transitory in the results of their action. Another demonstration is required, before the presumption thus established can approach to a certainty. We require proof to show that the disorders in which Tonics are used are blood-diseases. This does not seem to be difficult.