Page:Encyclopædia Britannica, Ninth Edition, v. 18.djvu/892

 856 PHTHISIS The causes influential in producing phthisis are numer ous and varied, but they may for general consideration be embraced under two groups, namely, those which are pre disposing and operate through the constitution as a whole, and those which are exciting and act immediately upon the organs implicated. These two sets of causes may be more or less distinctly associated in an individual case ; but, on the other hand, one may appear to act in both ways as predisposing and exciting. The following may serve to illustrate some of the conditions of a predisposing kind. A constitutional tendency to scrofula and its manifestations lends itself readily to the production, of phthisis. This morbid constitution is characterized among other things by a liability to low chronic forms of inflammation affecting gland -textures, mucous membranes, &c., the products of which show little readiness to undergo absorption, but rather to degenerate. Inflammations of this character affecting the lungs, as is not uncommon, have a special tendency to lead to the breaking down of lung-texture and formation of phthisical cavities. Many high authorities hold that tubercle-formation may be evolved out of scrofu lous inflammations of glands, such as those of the neck, by an infective process, like that already referred to. The mention of this constitutional state naturally suggests another powerful predisposing cause, namely, hereditary transmission. The extent to which this influence operates as a cause of consumption has been differently estimated by writers, owing probably to the various aspects in which the matter is capable of being viewed. It is impossible to deny that the children of parents one or both of whom are consumptive are liable to manifest the disease, that is, they inherit a constitution favouring its development under suitable exciting causes. But a similar constitu tional proclivity may be induced by other influences acting through the parents. Should either or both of them be enfeebled by previous disease or by any other weakening cause, they may beget children possessing a strong pre disposition, to consumption. Marriages of near relatives are held by some to induce a consumptive tendency, probably, however, owing to the fact that any constitu tional taint is likely to be intensified in this way. Phthisis is a disease of early life, the period between fifteen and thirty-five being that in which the great majority of the cases occur, and of these by far the larger proportion will be found to take place between the ages of twenty and thirty. The influence of sex is not marked. Occu pations, habits, and conditions of life have a very im portant bearing on the development of the disease apart altogether from inherited tendency. Thus occupations which necessitate the inhalation of irritating particles, as in the case of stone-masons, needle -grinders, workers in minerals, in cotton, flour, straw, &c., are specially hurtful, chiefly from the mechanical effects upon the delicate pul monary tissue of the matter inhaled. No less prejudicial are occupations carried on in a heated and close atmosphere, as is often the case with compositors, gold-beaters, semp stresses, &c. Again, habitual exposure to wet and cold or to sudden changes of temperature will act in a similar way in inducing pulmonary irritation which may lead to phthisis. Irregular and intemperate habits are known predisposing causes ; and over-work, over-anxiety, want of exercise, insufficient or unwholesome food, bad hygienic surroundings such as overcrowding and defective ventila tion, are all powerful agents in sowing the seeds of the disease. Consumption sometimes arises after fevers and other infectious maladies, or in connexion with any long- continued drain upon the system, as in over -lactation. The subject of climate and locality in connexion with the causation of phthisis has received considerable attention, and some interesting facts have been ascertained on this point. That phthisis is to be met with in all climes, and it would seem fully as frequently in tropical as in tem perate regions, is evidence that climate alone exercises but little influence. It is very different, however, with locality, elevation appearing to affect to a considerable extent the liability to this disease. It may be stated as generally true that phthisis is less prevalent the higher we ascend. The investigations of Dr H. J. Bowditch in New England and of Dr George Buchanan of the Local Government Board in the counties of Surrey, Kent, and Sussex agree in proving that elevated regions with dry- ness of soil are hostile to the prevalence of consumption, while low-lying and damp districts seem greatly to favour its development ; and it has been found that the success ful drainage of damp localities has occasionally had a marked effect in reducing their phthisis mortality. In all such observations, however, various modifying circum stances connected with social, personal, and other condi tions come into operation to affect the general result. As regards immediate or exciting causes, probably the most potent are inflammatory affections of the respiratory pass ages produced as the result of exposure. The products of such attacks are liable under predisposing conditions, such as some of those already mentioned, to remain unabsorbed and undergo degenerative changes, issuing in the breaking- down and excavation of the pulmonary texture. A neces sary consequence of the modern doctrine of the contagious nature and inoculability of tubercle has been to bring to the front a view as to phthisis once widely prevalent and in some countries e.g., Italy never wholly abandoned, namely, its infectiousness. By some supporters of the recent theories of tubercle it is maintained that phthisis is communicated by infection and in no other way, the infecting agent being the bacillus. Others, while holding the view of the specific nature of the disease, deny that it can be communicated by infection like -a fever, and cite the experience of consumption hospitals (such as that described by Dr C. T. Williams with respect to the Brompton Hospital) as to the absence of any evidence of its spreading among the nurses and officials. Others, again, deny both its specific nature and its direct infectious character. There appears, however, to be a growing opinion that phthisis may occasionally be acquired by a previously healthy person from close association with one already suffering from it, and, if this view be well founded, it affords a strong presumption that some infecting agent (such as the tubercle bacillus) is the medium of communi cation. The whole subject of the infectiousness of this disease is as yet unsettled ; but there appears to be suffi cient reason for special care on the part of those who of necessity are brought into close contact with patients suffering from it. Cases of phthisis differ widely as regards their severity and their rate of progress. Sometimes the disease exhibits itself as an acute or galloping consumption, where from the first there is high fever, rapid emaciation, with cough and other chest symptoms, or with the comparative absence of these, and a speedily fatal termination. In such instances there would probably be found extensive tuberculization of the lungs and other organs. In other instances, and these constitute the majority, the progress of the disease is chronic, lasting for months or years, and along with periods of temporary improvement there is a gradual pro gress to a fatal issue. In other cases, again, the disease is arrested and more or less complete restoration to health takes place. It is unnecessary to describe the symptoms or course and progress of all the varieties of this malady. It will be sufficient to refer to those of the ordinary form of the disease as generally observed. The onset may be somewhat