conveyed to offspring; and of producing morbid actions, which are thus, under the name of disease, frequently propagated through successive generations. Of the instances given, to which many others might have been added, it will be remarked that all are perfectly congruous with the common transmission from parent to offspring of external features of the body in the peculiarities of which no diseased action is involved. The wonder and the difficulty are alike for the two cases.

I have alluded to the distinction which may be made in treating this subject, between hereditary malconformations of particular organs or structures, and those diseases not less certainly transmissible by descent, where the blood must be looked to as bearing part in the phenomena. Most of the instances hitherto cited belong to the former class; but others can hardly be submitted to either, under the vague knowledge we yet possess on this obscure subject. All the questions, in truth, are of singular difficulty with regard to those diseases, where the hereditary evil is not of one organ or texture, but seeming to pervade every part of the body; showing itself at intervals, and especially at certain periods of life; - and frequently shifting its action suddenly from one part to another. Gout and scrofula in their various forms, and perhaps also the cancerous diathesis, will at once occur as the most familiar examples. The very difficulty of the research here affords presumption of the extent to which it may hereafter be applied, in extending and correcting our pathological views. In gout, for instance, admitting, what can scarcely be denied, a morbid ingredient in the blood as the cause of the disease, it may be asked whether hereditary gout depends on the transmission of some part of structure, favouring the formation of this matter? or on some faulty texture of the kidneys or other excreting organs, whose office it may be to remove it from the body? Or further, if it be that gouty

matter is merely an excess of some ingredient natural to the blood, whether the determination to the joints, forming the fit of active gout, is the effect of hereditary conformation of these parts; the absence of which peculiarity in others allows this excess to show itself in very different appearances of

disease?

I have noticed these questions more in detail, when treating elsewhere of this disorder. They apply equally perhaps, though this relation has been less followed, to those forms of acute rheumatism (a name unfortunately vague in its use), where there is every proof, from the nature of the symptomatic fever, from the peculiarity of the secretions and deposits, and from the metastasis to internal parts, — that the disorder is one of the whole habit, and probably depending on some peculiar state of the blood. There is sufficient evidence to show that this disease is often hereditary, and involving therefore the same questions as gout; though perhaps more dependant on occasional exciting causes from without, and less marked as a temperament of body.*

Many similar inquiries will apply to the scrofulous or tubercular constitution; admitting it, indeed, as a single form of cachexia. It may be asked whether this congenital temperament consists in a certain texture of solid parts, vascular or otherwise, giving liability to peculiar deposits at certain periods of life? or whether, in a specific morbid state of the circulating fluids, producing such deposits in the parts of the body most prone to receive them? The latter view, as in gout, may be admitted as the more probable one, and for the same reasons. Indeed, however different the diseases in many respects, yet certain general relations of character sub

The most ample proof is that furnished by the large experience of Chomel, who rates as high as one half the proportion of rheumatic cases where the parents had suffered under the same disease.

sist between gout and scrofula; - in their hereditary nature; in their respective connection with particular periods of life; in the proofs of a morbid matter peculiar to each; in the variety of forms in which this morbid cause shows itself in different persons; and in the frequency and facility of translation from one part to another. These analogies lead us to no common cause; but they show causes operating by certain common laws; and, in a case where there is still so much to be learnt, all such relations are of value. Hereafter we may be able, by these and similar means, to associate together diseases now widely apart in our nosologies;-gaining thereby a classification more just, and of greater practical usefulness, than any we now possess.

In the scrofulous temperament, even more than that of gout, we have a remarkable diversity in the forms the disease takes, and the organs it attacks. But it is worthy of note, that there appears a general tendency to the same form in the same branch of a family thus affected; still more in children of the same parents. I may mention, as a striking example, the number of cases of blindness, partial or complete, in some families where this temperament exists. In others, the disposition is as strongly marked to affections of the joints; in others, again, to pulmonary consumption in its more common form. These are instances of the tendency to specialties before noticed, extending to morbid structure or functions, as well as to those of healthy kind.

What has been just said of the scrofulous diathesis applies by parity of all essential characters to the carcinomatous habit. Though the proofs are more limited by the comparative infrequency of the disorder, it is certain that this also is often an hereditary disposition of body, tending to the production of morbid growths, more especially at certain periods of life. If, as alleged, the lymphatic temperament is that particularly

disposed to carcinoma, the question again arises (but without any further facility for solving it), whether this connate tendency consists in a state of the solid tissues, or of the fluids circulating through them? In using the term of lymphatic habit, we are not, indeed, entitled to carry our meaning beyond some of the more obvious effects of a constitutional cause, the nature of which, whether affecting the solids or fluids, is still unknown to us.

Certain general facts still remain to be stated on the subject of hereditary disease; some of them of deep interest, but of equal difficulty. One of these is, that singular variety in the general law which Duchesne and others have termed Atavism; where a bodily peculiarity, deformity or disease, existing in a family, is partially or wholly lost in one generation; reappearing in that which follows, or even yet later. A curious instance of this has been already mentioned, where the omission depended on change of sex in the series. There may be many analogous cases, in which the part of structure affected by hereditary disease admits of the malady being disguised, or superseded, by other casualties in the bodily conformation of the individual. Or, if the animal fluids be directly concerned in the transmission, we may conceive these liable to be more readily affected by causes of variation, so that the same morbid influence is directed to one part rather than another, assuming totally different aspects of disease. But these explanations, probable though they may be in part, will scarcely apply to the numerous cases where, the sex and all obvious circumstances being the same, a disease or deviation from common structure is missing in one or more individuals of a family series, recurring in their children. Here we pass at once into the obscurity which hangs over all that belongs to that great function of life, the reproduction of the species. But the same analogy, or rather unity of

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plan, is still present to us. If one generation escapes the transmission of an hereditary disease, so do we often find some strongly-marked feature of face or figure lost in one of a family, but reappearing in the children. The proof is hereby strengthened of that general relation which pervades all these phenomena, and which makes the simple resemblance of an external feature the exponent of other cases, in which the most severe diseases are conveyed from parent to offspring.

Connected with the foregoing is another curious variety in the transmission of disease, if so it may be termed, which has been very little noticed by medical authors. I allude to the case of several children of a family being affected in common with some given malady, of which there has been no certain instance on the side of either parent. An example has lately occurred to me in one family, of three sons and a daughter, every one of whom underwent an attack of hemiplegia before the age of forty-five, though neither father nor mother had been similarly affected. I find another instance in my notes, where three brothers severally suffered hemiplegia, and about the same period of life, without any record of the like event in the family. I have recently seen a fatal case of cerebral disease, with epileptic fits, in a young lady of twenty-four; two sisters of whom had died about the same age with similar symptoms, though neither parent had been subject to such disorder. I am acquainted with a family in which four children have died during infancy from affections of the brain, without any like instances in the family on either side. In another family, without any similar disease in the parents, three or four children had epileptic fits.

I have notes of several similar instances; chiefly, as I think, but not exclusively, disorders of the brain and nervous system. I have known three cases of Diabetes mellitus in brothers, under ten years of age, in the same family; one