Against these proofs it has been urged that the nervous system has certainly an influence over this disorder, for that a sudden alarm has been known to arrest it. But this may occur also with other blood-diseases, and it does not prove that the nervous system is at all connected with their origin. It can hardly be supposed that Goitre or Scrofula is ever caused by a derangement of the nerves. And yet Baron Alibert relates an authentic case of a French lady who had a large goitre, which for a long time resisted all treatment, but which nevertheless disappeared entirely during the brief Reign of Terror in the French Revolution. In addition to these arguments it may be urged that Ague is often, if not always, connected with deranged hepatic functions, a fact that again points out that disease as a blood-disorder. Seeing then that the medicines of this order of Tonics differ in each particular of their action from those remedies which influence the nerves directly, and that the diseases in which they act beneficially are essentially blood-diseases, there are sufficient grounds for concluding them to be Hæmatics, or blood-medicines. We have now to consider the remaining minor propositions, which treat of their action as Restoratives; to ascertain whether they have been rightly allotted to this division. Are there in healthy blood any substances which resemble them? This will appear to be a question of no small difficulty, when it is considered how little information we have actually obtained respecting the chemical composition of the vital fluid. It is nevertheless desirable that we should inquire into it to the best of our ability. During the last few years, many propositions, intended to throw a light upon physiological science, have emanated from the fertile pen of M. Liebig of Giessen, who is rightly and universally ranked among the most illustrious of modern chemists. There are two which especially bear upon the present subject. In his first work on Organic Chemistry (p. 182,) he argued, that whereas the alkaloids Quina and Morphia resembled the brain substance in their chemical constitution, they were therefore enabled to exert a direct control over that organ by influencing its nutrition. But it is impossible to accept this explanation. The composition of the brain has been since more accurately investigated, and it has been shown to consist mainly of a mixture of albumen and fat. Now there is no reason why these substances should have a special affinity for albumen and fat in the brain, any more than for the same elements in other parts of the body. There is also no analogy at all between Quina and Morphia as medicines beyond their resemblance in chemical constitution. The theory seems to be altogether groundless.