phthisis is a common disease in the child. The term signifies ulceration of the pulmonary tissue. The affection is therefore perfectly distinct from acute tuberculosis. The latter is a general disease in which the lungs, if they are involved at all, are affected in common with most other organs of the body, and if they undergo disintegration, break down as a consequence of inflammatory changes due only indirectly to the presence of the grey granulation. Pulmonary phthisis, even when the con sequence of a general dyscrasia, is especially a lung disease, which if it run its course unchecked passes on necessarily to softening and excavation.
Phthisis may be acute or chronic. The acute form is not uncommon in young subjects, and consists in rapid hepatisation and caseous infiltration of the lungs, with equally rapid softening and disintegration. This form of the disease is to be distinguished from acute pulmonary tuberculosis, although it may be combined with it.
Chronic phthisis is seen in two principal forms, viz., chronic tubercular phthisis and catarrhal or pneumonic phthisis. These varieties differ mark edly in their mode of origin, their course, and often in their termination, and are, no doubt, the consequence of very distinct pathological conditions.
Causation. —Most cases of pulmonary phthisis are dependent upon a general predisposition, which may be hereditary or acquired. The child may be born into a consumptive family and thus inherit a constitutional delicacy which renders him especially sensitive to morbific influences. On the other hand, although without any family tendency to this form of ill ness, the patient may yet, through the agency of special disease, aided per haps by insanitary surroundings, acquire a pulmonary which sooner or later, under suitable conditions, developes phthisical changes in the lung.
The inherited disease may consist of either form of phthisis ; and either variety may be acquired by a child in whose family no tendency to consumption can be discovered. Even chronic tubercular phthisis, Al though in the majority of cases no doubt the consequence of an inherited predisposition, may be excited by infective agency through the presence of softening cheesy matter at some part of the body. A special pulmonary
delicacy is often the consequence of whooping-cough and measles. These diseases are very liable to be complicated by catarrhal pneumonia, and it often happens that after convalescence the absorption of the consolidating material is incomplete. Consequently a caseous lump is left at some part of the lung, which after remaining inactive for a shorter or longer period begins at length to soften and set up irritation in its neighbourhood. But even if perfect absorption of the consolidating material take place, a certain susceptibility may be left after the subsidence of the inflammation, so that the child becomes attacked again and again by obstinate catarrhs. These catarrhs in favourable subjects are apt to lead to cellular infiltration of the bronchial walls and gradual invasion of the alveoli. In this way a catarrhal or pneumonic phthisis is eventually developed.
In children of scrofulous tendencies there is very commonly a pulmo nary weakness. The child is very subject to catarrhs, and he has also the proneness inseparable from his strumous constitution to rapid prolifera tion and caseation of cellular elements. In such a subject a catarrhal phthisis is readily set up. So, also, in subjects especially prone to tuber cular formation the lung irritation may induce this variety of pathological change. In the present day, owing to the discovery by Koch of the tuber cle bacillus, there is a tendency to look upon all forms of phthisis as due to infective agency. According to this view, the various pathological condi tions would be all tubercular, as the bacillus appears in most cases to be discoverable either in the sputum or the pulmonary tissue of the part affected. The question, however, is as yet far from settled ; and looking at the wide differences in the clinical characters of the several forms of pul monary phthisis, it seems desirable to consider these diseases from a clinical rather than from an anatomical point of view.