this: That the connection between the diagnostic symptomatology of typhoid fever and the entero-mesenteric lesions is, I will not say absolute and invariable, but as nearly so as the connection between the diagnostic symptoms and the characteristic lesions of any given disease whatever in the nosology, in which this connection is not established by positive physi cal signs.

CHAPTER IX.

THEORY.

I believe that it will be a phenomenon in medical writings to find an essay on such a disease as fever unattended by a theory of its proximate cause. Yet were it as well if the professor who spends months in exciting the wonder of applause of a juvenile audience with phraseology which he does not himself understand, would substitute, for all this waste of words and time, the confession of his own and the general ignorance.-JOHN MACCULLOCH.

THE most positive thing that can be said under this title is, that the materials for a complete and philosophical theory of fever, or theory of any individual fever, using this phrase in its ordinary acceptation, do not exist. Such a theory presupposes and involves a knowledge of the intimate processes and relations of the living powers which has not yet been attained. It is very questionable even whether such knowledge is attainable.

In order to see clearly the truth of these observations, and the extent of this truth, let us inquire for a moment what some of the elements are which must go to make up this knowledge; what their nature is, and in what they consist. In the first place, we must know what the actual efficient causes of any given fever, or form of fever, are. We must know what that agency or combination of agencies is, which, being present, brings into existence, originates, sets in motion that concatenation of disordered actions, that complex combination of morbid processes, which constitutes the fever. We must know in what manner these agencies act; where they make their impression; and in what the modifications consist which they work in the living organization and its properties. Of all these things, we are utterly and profoundly ignorant. In the second place, we must know the seat and character of all these processes and modifications themselves; their peculiarities; their tendencies; the differences which exist between them in the several forms of febrile disease. We must know their relations to each other. We must know which amongst them are primary and

essential; which are secondary and accidental. We must know the parts which they severally play in the production of the integral disease. Of these things, also as of the causes of fever and their mode of action, it is not too much to say that, if we are not wholly and profoundly ignorant, we are so to a great extent. They are but very partially and imperfectly known to us. They are known to us rather analogically, if I may so speak, and by comparison. with other morbid processes, than absolutely and positively. We can see wherein they differ in many respects from these other processes, and wherein they resemble them. With these limitations, and under the conditions implied by these remarks, there is no reason why we may not attempt to commence the foundation of a theory of fever. But in the present state of science, it can only be an attempt at a commencement. We may endeavor to interpret the connection and relationship which observation has shown to exist between certain phenomena or groups of phenomena. We can do nothing more.

It ought to be unnecessary to say that even this can be done only by confining ourselves to a single well-defined individual form of fever. Under the simplest conditions, and where alone it is in the nature of things at all possible, we shall find this interpretation or theory sufficiently obscure and difficult. When attempted, as has generally been the case, under other conditions, it has proved utterly futile; when applied, as these interpretations and theories have generally been applied, to unascertained and imaginary states of the system, they have always degenerated, necessarily, into the idlest of all conceivable speculations. There is no such individual disease as that which has always been expressed, and which is still expressed by the term fever. How then can there be any theory of fever? There are many separate diseases, to which this generic name is properly enough applied, on account of certain general analogies which exist between them. But the disordered actions and processes which constitute one of these diseases may differ essentially; and, as far as we can ascertain, in most cases they do so differ from those which constitute another of these diseases. The theory of one fever, then, must be wholly or to a great extent inapplicable to another. The elements which enter into the composition of one problem are not to be found in the other, or they are present in different proportions. The word fever, when used as it commonly is to designate a disease, has no intelligible signification. It is wholly a creature of the fancy; the

offspring of a false generalization and of a spurious philosophy. What, then, can its theory be but the shadow of a shade?

If the true theory of disease be such as I have represented it, we should naturally look, in its application to any individual and separate form of disease, first and principally to those phenomena which are most constantly present, and which seem to constitute its most important elements. According to this rule, and in relation to the subject immediately before us, the theory of typhoid fever, the first inquiry would naturally be, what is the nature and what are the relations of its characteristic lesion-that of the elliptical plates of the ileum? A satisfactory answer to these questions would so far settle the theory of the disease.

What is the nature of this alteration of Peyer's glands? Does it consist in an inflammatory action, and its results? If so, is the inflammation common and simple; or has it something peculiar and specific in its character? We can hardly hesitate, I think, in attributing this lesion to inflammation. We know nothing of any other morbid process that can produce similar results. In its early stages, we find the tissues which are its seat tumefied and reddened; subsequently, ulceration takes place; and if life is not destroyed, there is abundant evidence that the restorative process is set up and the lesion removed by complete cicatrization. Their enlargement, softening, redness, and in some instances the presence of pus in their substance, are equally sufficient proofs that the affection of the mesenteric glands is also of an inflammatory character. But as to the second point, it seems to me that all the analogies in pathology tend to show that this inflammation is not common, but specific. It is circumscribed, and not diffused, as ordinary inflammation of the mucous tissues usually is. It does not often lose itself gradually, shading off into healthy membrane. The morbid process almost constantly extends to the subjacent cellular membrane, which is almost never the case in common mucous inflammation of an acute character. Its tendency to rapid ulceration, and the appearances of some of its morbid products, would also seem to show that it has something special and peculiar in its nature. Is it not also philosophical and fair to infer something in corroboration of these views from the observations of Andral and Gavarret in regard to the condition of the blood in different diseases? They have found, from extensive and careful examination, that, in all diseases consisting of common, open, frank inflammation in any of the organs, or complicated with such inflammation, the relative quantity aud

proportion of fibrin in the blood are increased; while in diseases of an opposite character, and under opposite circumstances-in the exanthemata, for instance-the fibrin either merely maintains its natural proportions, or is diminished in quantity; a condition, as we have already seen, characteristic of the blood in typhoid fever.

In regard now to the relation between this lesion of the elliptical patches on the one hand, and the disease considered as a whole on the other, or between the lesion and the symptoms, the simplest view to be taken is that which makes the disease consist essentially in the lesion, and which refers the symptoms to the lesion as their cause. This doctrine makes typhoid fever, not an essential or idiopathic fever, but an enteritis, or a follicular enteritis, or a dothinenteritis, and assigns to it a nosological position amongst the local phlegmasiæ. This is a modification merely of the great doctrine of Broussais, and a modification only so far that it does not include the mucous membrane of the stomach in the lesion. It is still held, partially at least, by some French pathologists of the present day. It has been, strangely and unaccountably enough, even by men who have read his books, attributed to Louis. Dr. O'Brien, of Dublin, in one of his hospital reports, when speaking of this subject, says: "M. Louis, in particular, has adopted the theory of Broussais in its fullest extent." The samé misapprehension has been fallen into even by such a man as Dr. Christison. It is, however, so far from being true that Louis has ever adopted the doctrine of Broussais in relation to the nature of fevers, that no other observer has done so much in overthrowing his peculiar principles. He has even been the most formidable and successful antagonist of that extraordinary man; opposing, in the calm confidence of a truthloving and truth-seeking spirit, to the arrogant assertions and to the seductive generalizations of the highest genius-maintained and vindicated as they were by a strength and an eloquence of language unequalled in the annals of medical literature-the impregnable and serried array of facts and their relations, carefully and positively ascertained. One objection to this view of the nature of typhoid fever consists in the circumstance that there is no uniform proportion between the extent of the local disease and the severity of the symptoms. There are many fatal cases in which the intestinal lesion is very limited in extent; there are others, where the whole character of the disease has been unusually mild, and in

Dublin Med. Trans., p. 313.