It must not be inferred, from what has been said on the importance of blood-medicines, that I am disposed to agree with those who would account for all diseases by some fault in the humours of the body. For though we know that many cases of convulsive disorder, as of Hysteria, Chorea, and Epilepsy, may be reasonably accounted for by supposing the existence of a wrong in the blood, which has affected the nervous system,--yet there are doubtless many nervous affections which are primarily independent of the blood, which can only be treated by Neurotic medicines, and even then often without benefit. Thus far I have chiefly dealt in assertions on the subject of Hæmatic medicines, but I am now about to attempt a thing which is more difficult, that is, positive proof. I shall treat separately of Restoratives and Catalytics; each division will be divided into certain distinct orders of medicines; and of each of these orders in turn I shall attempt to prove what is laid down concisely in Proposition VII. To simplify this proof, that part of the Proposition which relates to Restoratives will be divided first into a number of minor propositions, which, taken together, imply the original one. Each must be shortly proved applicable to each order of Restoratives. The same will be subsequently done with Catalytics. Having sustained the original proposition to my own satisfaction, I shall, in some cases, venture to offer an additional hypothesis--only as hypothetical--on the action of particular medicines. Let us now proceed to the consideration of the first division of Hæmatic medicines. RESTORATIVES. The general name given to the medicines in this division is founded upon a fact relative to their action, which will be acknowledged of most that I have here included--namely, that they restore to the blood certain materials in which it is deficient.[31] I will divide them into six orders, which are all distinct and characteristic in their mode of action. RESTAURANTIA. Ord. 1. Alimenta. Ord. 2. Acida. Ord. 3. Alkalia. Ord. 4. Tonica. Ord. 5. Chalybeata. Ord. 6. Solventia. On reverting to Proposition VII., which treats of the action of the first class of medicines, it will be seen that what has been there stated with respect to the action of Restoratives resolves itself into the following simple affirmations or minor propositions. _m. p._ 1.--That they act in the blood, and that their effect is permanent. _m. p._ 2.--That there are naturally in the blood substances which resemble or coincide with them. _m. p._ 3.--That they are not of necessity excreted, but may remain in the blood. _m. p._ 4.--That they are of use when a disease depends on the want of one or more materials in the blood.