From the view I have given of the state of the blood-vessels in fever, the reader will perceive the difference between my opinions and Dr. Brown's upon this subject. The doctor supposes a fever to consist in debility. I do not admit debility to be a disease, but place it wholly in morbid excitement, invited and fixed by previous debility. He makes a fever to consist in a change only of a _natural_ action of the blood-vessels. I maintain that it consists in a _preternatural_ and convulsive action of the blood-vessels. Lastly, Dr. Brown supposes excitement and excitability to be _equally_ diffused over the whole body, but in unhealthy proportions to each other. My theory places fever in excitement and excitability _unequally_ diffused, manifesting themselves, at the _same time_, in morbid actions, depression, and debility from abstraction, in different parts of the body. No new excitement from without is infused into the system by the irritants which excite a fever. They only destroy its equal and natural distribution; for while the arteries are in a plus, the muscles, stomach, and bowels are in a minus state of excitement, and the business of medicine is to equalize it in the cure of fever, that is, to abstract its excess from the blood-vessels, and to restore it to the other parts of the body. II. I come now to apply the theory which I have delivered to the explanation and description of the different phenomena or states of fever. I have said in my sixth proposition that there is but one fever. Of course I do not admit of its artificial division into genera and species. A disease which so frequently changes its form and place, should never have been designated, like plants and animals, by unchangeable characters. The oak tree and the lion possess exactly the same properties which they did nearly 6000 years ago. But who can say the same thing of any one disease? The pulmonary consumption is sometimes transformed into head-ach, rheumatism, diarrh[oe]a, and mania, in the course of two or three months, or the same number of weeks. The bilious fever often appears in the same person in the form of colic, dysentery, inflammation of the liver, lungs, and brain, in the course of five or six days. The hypochondriasis and the hysteria seldom fail to exchange their symptoms twice in the four and twenty hours. Again: the oak tree has not united with any of the trees of the forest, nor has the lion imparted his specific qualities to any other animal. But who can apply similar remarks to any one disease? Phrenitis, gastritis, enteritis, nephritis, and rheumatism all appear at the same time in the gout and yellow fever. Many observations of the same kind might be made, to show the disposition of nearly all other diseases to anastomose with each other. To describe them therefore by any fixed or specific characters is as impracticable as to measure the dimensions of a cloud on a windy day, or to fix the component