242 



SCIENCE. 



[Vol. XV. No. 376 



of the disease. The native races of America were free from 

 coasumptioQ till they came in contact with Europeans, and 

 began to adopt their habits and mode of life; and the amount 

 of this disease actually present in the American Indians has 

 recently been shown to correspond with the extent of their 

 civilization.^ So, also, were the South Sea Islanders, the 

 Maories, the New Britons, and the natives of the African 

 coast. The same process is now marking the progress of 

 civilization among the natives in the interior of Africa, Asia, 

 America, and New Britain. We have the same sequence 

 of events in the great mortality of the dark races that settle 

 in our cities and large towns; and in civilized countries the 

 classes that were formerly free from consumption, for ex- 

 ample, mountaineers and our own Highlanders, are now 

 being attacked by the disease, as the direct result of a corre- 

 sponding change in their habits and surroundings. 



What is the mode of operation of the conditions that tend 

 :'to reduce the breathing capacity in the production of con- 

 sumption? In a true state of health the lungs have a suffi- 

 cient breathing surface, not only to perform their ordinary 

 functions, but also to meet within certain limits any extra 

 demand that may be made upon them. When they are sub- 

 jected to conditions that tend to reduce the breathing ca- 

 pacity, they lose this power of adjustment to their external 

 .conditions, and subsequently become unable to effect the 

 whole amount of those interchanges that constitute their 

 ordinary function. That part of those interchanges that is 

 not effected by the lungs, being necessary to meet the ordi- 

 nary requirements of the bo.ly, will be at once added to the 

 work normally performed by one or more of the other organs ; 

 and, so long as this compensatory work is accomplished 

 without causing a disturbance of their functions, a tempo- 

 rary adjustment will have been effected, and there will be 

 no obvious disturbance of the general health. But unfor- 

 tunately these conditions continue in active operation, there 

 is progressively increasing reduction of the breathing capa- 

 city, and consequently there comes a time when this com- 

 pensatory work is not effectively performed by other organs, 

 and there is either a greater pressure of work thrown on the 

 lungs, or over-activity of one or more of the other organs, 

 indicated by some mode of disturbance of the general health.^ 

 The imperative demand for the effecting of these inter- 

 changes causes in the parts least able to meet it, as a rule 

 the apices, the phenomena of irritation, which is, as we know 

 from the experimental production of tubercles by irritation,^ 

 manifested by tubercular change. Each point of these 

 morphological changes produces a further reduction of the 

 lung capacity, and by so much becomes an addition to the 

 forces that increase the inequality between the amount of 

 lung available and the amount of work it has to perform; 

 And so there is more irritation of the lungs, and more work 

 thrown on the other organs, disturbing their functions and 

 deranging the general health. Further, as the foci of mor- 

 phological change multiply by reason of the progressive 

 increase of the conditions that produce them, there is in- 

 creased pressure and lessened supply of nutrition, accom- 



I Rush (Philadelphia), Science (New York). 



•5 Pollock, Hanot (Jaccond's Dioiionary), Ruchle (Ztemssen^s), etc. 



■3 Wilson-Fox, Sanderson, Simon, Cohnheim, Frankel, etc. 



panied by local congestion ; so that they become deprived of 

 nutrition, necropsis takes place, and eventually cavities are 

 formed. Hence there is more and more work thrown on the 

 other organs, causing increasing disturbance of their func- 

 tions, and consequently more and more disturbance of the 

 general health, till first one orgao and then another becomes 

 so greatly deranged that the so-called complications of the 

 disease are pi'oduced; and this process goes on till at last 

 neither lungs nor the other organs are together able to effect 

 those interchanges without which life cannot continue. 



Glance for a moment at the course of consumption when 

 viewed in the light of this interjiretation of its nature. In- 

 stead of its "uncertain and mysterious" advent, its "pro- 

 tean" forms and "chameleon" changes, we now see before 

 us a perfectly natural succession of events, whose raison 

 d'etre order of sequence and relationship to each other can 

 be laid down with exactitude. We have, in the first place, 

 the lowered or arrested vital capacity progressively decreas- 

 ing, associated with a progressive decrease or arrest of the 

 size and extent of movement of the chest, the wasted or non- 

 developed muscles, the sloping shoulders, and the changing 

 shape of the thorax. At a certain point in this course there 

 appear occasional, and then frequent, indications of increased 

 activity of one or more of the other organs; there is increas- 

 ing liability to " catch colds," and increasing difficulty in 

 getting rid of them; and there are signs of the derangement 

 of the general health and increasing weakness, accompanied 

 by indications of lung irritation and implication. This may 

 be followed by a period of rest; there has been a temporary 

 adjustment between the work to be done and the work 

 effected; and in common parlance the patient has been 

 "patched up," if he is under treatment. Then the area of 

 lung implication spreads, the signs of lung irritation become 

 more marked and troublesome, the general functions are 

 greatly deranged, the appetite fails, the body-weight seriously 

 decreases, hectic is present, and the patient's rest is disturbed. 

 This also may be followed by a period of rest, a balance 

 having been effected between the work now required and 

 that accomplished. And these periods of attack and rest go 

 on, the attacks increasing and the rests disappearing, until 

 so much destruction has been effected that the body is no 

 longer able to resist the disease, and death terminates this 

 unequal combat. 



Whatever condition of man's habits, mode of life, and 

 surroundings has a tendency to reduce the breathing 

 capacity is a potential cause of consumption ; and it is an 

 active cause in its production, unless and until its action is 

 counteracted or compensated. It is evident that we have 

 not to deal with the mere temporary or accidental presence 

 of such conditions, but with those only that have a continu- 

 ous or permanent character. We may consider these con- 

 ditions from the point of view of whether their tendency is 

 expressed by disuse of the lungs or by their forcible com- 

 pression or injury. The most important place in the former 

 must be assigned to the rapidly decreasing amount of mus- 

 cular exertion we require to make in order to supply our- 

 selves with those things that are necessary for our daily 

 wants, owing to the increasing facilities for obtaining them 

 afforded us by means of machinery and railways. This 



