question,) must be to ascertain whether the same causes would not entail the development of any other equally chronic disease?

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Many persons have no doubt made the same reflections, and nevertheless I have not thought it right to suppress the expression of them here, because the study of the etiology of diseases is generally undertaken with great levity, even by men of high acquirement. In truth, one would imagine, judging from the manner in which the subject is generally handled, that some slight general knowledge, supported by a little more or a little less common sense, is quite sufficient to fit its possessor for the discovery of the causes of disease, even of those of the chronic class;-in other words, to qualify him for the solution of the most complicated problem within the whole range of pathology.” * "How often do we see children," says Billard, “born with all the appearances of flourishing health, become feeble and sickly from diseases, which attacking them in their early infancy, leave after them organic modifications, which time can scarcely remove, and which in some individuals never disappear! It is perhaps to a congestion or a pneumonia after birth-that short breathing, husky voices, asthmas, or idiopathic coughs, with which some individuals are affected, are to be attributed."†

Since our own attention has been drawn to the sub

*Researches in Phthisis.-Ante, p. 486.

Treatise on the Diseases of Infants.-Ante.

ject of etiology in this point of view, we have more particularly observed persons who have suffered more or less all their life from pulmonary affections; and on one occasion our informant expressly stated, that it "was no wonder her chest was weak," for her mother had told her" she was born with a cough."

It is well known how variable is the course, and how often perplexing the complications and sequelæ, of the most common maladies in childhood,—measles, pneumonia, hooping-cough, and scarlet-fever. They vary in their stages, times, symptoms, and intensity. These variations are frequently attributed to occult states of the atmosphere,--malaria, the constitutio anni, or to some other external condition. But allowing for the full effect of these conditions, there are residual phenomena unaccounted for. It frequently happens that numbers of children, previously to all appearance in perfect health, become affected by epidemic disorders; enter upon dentition, pneumonia, measles, scarlet-fever, &c., under the same external conditions-at the same time and from the same source, in the same family, and in the same house. Yet how different the symptoms, stages, and duration of the malady; and how various the complications and sequela. Some are speedily cured or recover; others take a longer time: some fall at once into a scrofulous or asthenic inflammatory disease; others linger, and at last succumb to some distant supervening malady. In these cases,-all other circum

stances and conditions having been estimated,-the residual phenomena can be explained only by the previous history of the child; by difference of constitution, consequent upon anatomical states, remaining from the perfect or imperfect cure of former maladies. And here, let it be observed, that the word imperfect, does not refer to any thing which the physician or surgeon could have done better, but to the laws of morphology, by which the cures have been effected. From preceding facts and observations arising from the application of the microscope to morbid anatomy, we feel entitled to draw the following conclusions :

First.-Anatomical changes or states remain after the cure of wounds and diseases, which possess more or less of permanency, and though not evolving symptoms, yet affect the future health of the person.

Secondly. These anatomical states are veræ causæ for differences of constitution or diathesis,-because the aggregate expression of the whole cannot be the same when important parts are altered. And, in the lung, they are predisposing causes of consumption; because, from an universal law, the nutrition of natural textures in contact with unnatural states, is disposed upon slight events, to go back to the general, rather than keep up to the special form.

These conclusions establish the necessity of attending, in infancy and youth especially,-not only to the symptoms or phenomena of the chief malady and its attendant complications, but to the time, progress, and

results of the cure. In dismissing a patient from medical care and treatment, no opinion can be accurately formed or expressed, concerning anatomical states without symptoms, remaining from or after the cure. The practical rule in this difficulty would seem to be, that if, on the recovery of a personan infant or youth-from a severe malady, the constitution be in any obvious manner changed, the fact is to be accepted as proof of the presence and operation of persistent anatomical changes. What these changes are-when there are no local or special functional signs-and when the person is living, we can go no further than presumption in deciding. But the frequency with which supervening granulations and tubercles occur in the lungs and fibrous textures, as made known to us by inspection after death, in children dying of all diseases, may be taken as a ground of the probability of these changes being a state of that nature. The facts are, that a severe illness has occurred, and a recovery taken place; but the constitution is weaker and more delicate than before. And it is safer, in doubtful cases, as leading to greater watchfulness and care, that our presumption should rather exceed, than that it should fall short of a stern reality. But whilst prepared to look danger in the face and provide against it, there is no need to run into the opposite extreme and imagine every delicate person to be threatened with consumption.

It is a practical corollary from the conclusions just

stated, that the living population, amongst whom the duties of the healing art are exercised, is divisible into two classes, those with an undamaged organization, and those who bear within them the persistent marks of previous maladies and cures. This division has no reference to sex or age, or position in life,-rich or poor; but to the structural changes-the stateswhich bygone diseases have from infancy upwards stamped upon the organism.

And here it is essential to the fulness necessary for practical purposes, that another point of discrimination brought out in our researches be borne in mind, namely, between the anatomical states resulting, necessarily, from the most perfect cure;—as the cicatrix of a burn -adhesions of the lung to the wall of the chest in pleurisy, adhesion of the pericardium to the heart in pericarditis, opacities of the cornea after ulceration,— hardened lobules in atelectasis, &c., and those supervening anatomical states, of which tubercles in the fibrous, and ulceration of the mucous membranes are types and examples. Both may be veræ causæ of a more or less well marked delicacy of constitution; but in the former examples, a conformable morphology has taken place, the texture has made as good a recovery as the case admitted of; whereas the latter are defects, involving the essential anatomical condition of a scrofulous diathesis. Hence, therefore, the weakly or delicate class is properly divisible into two sub-classes, -the one, delicate from the unavoidable results of a