240 



SCIENCE. 



[Vol. XV. No. 376 



is comparatively rare in pure wet, undrained districts, and a 

 majority of consumptive patients have not been subjected to 

 the influence of dampness of the soil. The theory of the in- 

 heritance of consumption is still generally accepted, although 

 no evidence has been adduced in its support. At birth the 

 child of consumptive parentage has the same type of chest, 

 the same proportion of chest-girth to height, as-that possessed 

 by children of healthy parents, and there are no means of 

 distinguishing the lungs of the one from those of the other. 

 The fact that some of the children of consumptive parents 

 subsequently themselves suffer from this disease is not evi- 

 dence that consumption was transmitted from the parents to 

 those children. A large number of children, even where 

 both parents have died from consumption, remain absolutely 

 free from it.' Is it so unreasonable to expect the conditions 

 that produced the disease in the parents will later on repeat 

 the process in those of the children that are submitted to 

 their action, that we must resort to a pure hypothesis for an 

 explanation of those facts? The theory is only alleged to 

 account for a small part of the cases of consumption, and 

 we cannot accept an hypothesis where we already have a 

 reasonable explanation of the subject. 



I jjass now to the theory that the Bacillus tuberculosis is 

 the cause of consumption, and I ask. What evidence is there 

 to prove this theory? Koch^ experimentally introduced the 

 bacillus into a number of animals, some of which were in- 

 variably attacked by consumption, others had a greater or 

 less liability to it, and the remainder were totally free from 

 the disease. We have to examine the successful experi- 

 ments. They were made upon animals that were most liable 

 to "spontaneous" consumption, and their value rests upon 

 the fact that the animals that were not inoculated were found 

 healthy. Now, Koch himself noted, that, if these animals 

 were kept too long before they were, inoculated, they also 

 became diseased. So there was only a difference of time be- 

 tween the inoculated and non-inoculated animals that became 

 consumptive, and consequently the value of the so-called 

 "control" evidence entirely disappears. 



What produced consumption in the non-inoculated ani- 

 mals? According to the theory, the inhalation or other in- 

 troduction of the bacillus. Just so; but where is there any 

 evidence of that? The previous experiments do not prove 

 that the bacillus can produce consumption, and to offer that 

 explanation is to assume the precise point, the experimeots 

 were intended to prove.^ Further, these animals were sub- 

 jected to the conditions of confinement. What effect did 

 those conditions produce on the animals? Koch ignored 

 them and their effects, and by so much vitiated his conclu- 

 sion, even if that conclusion had been otherwise established. 

 The bacillus, its containing medium, or the changes effected, 

 were evidently powerfully irritant; and it would indeed be 

 surprising if, when introduced into animals so liable to con- 

 sumption and subjected to the conditions of confinement, 

 the disease were not both more rapidly manifested and of a 

 more extensive character. Therefore Koch's experiments do 



1 Thompson. 



' Report of Koch's Experiments (British Medical JoumaO, Watson, Cheyne, 

 Spina (^Sutler). 



s Gadenl arifl Malet's Experiments (British Medical Journal), Brown-Se- 

 quard's Experiments (Lancet). 



not in any way warrant the inference he has drawn from 

 them ; and once again a great discovery has liad its true im- 

 port temporarily overshadowed by a misinterpretation of its 

 real significance. 



How does this theory accord with the known facts of the 

 case? Tubercles in various stages, young and adult, are 

 found in which there are no bacilli, while in the same speci- 

 men caseous tubercles may be present containing bacilli.' 

 There are cases of consumption in which the bacillus is absent 

 both during life and post-mortem} The physicians, clinical 

 clerks, nurses, post-mortem room attendants, and those wha 

 clean the wards of consumptive hospitals, are not attacked 

 by the disease.^ Patients suffering from bronchitis, pneu- 

 monia, etc., occupy beds adjoining consumptive patients for 

 long periods, but they do not become consumptive. The 

 friends of patients who regularly visit them in these institu- 

 tions do not get it. Some wards at Brompton had their 

 ventilating-shafts stopped, but no attack of consumption fol- 

 lowed either in the patients suffering from other chest com- 

 plaints or in the attendants.* These institutions are not 

 centres from and around which the disease spreads. Yet 

 here are the most favorable conditions for its rapid and un- 

 questionable propagation ; and we have only to substitute 

 small-pox, scarlet-fever, or any of the infectious diseases for 

 consumption in the above conditions to realize what must 

 happen if it were an infectious disease. And so widely is 

 this bacillus distributed, so tenacious is it of life, and s» 

 constantly are we, especially when suffering from respira- 

 tory diseases, exposed to its action, that on the assumption 

 of its potency it is impossible to account for the comparative 

 smallness of the number of consumptives. 



We pass from these contradictory and most unsatisfactory 

 theories to the consideration of one that is both in strict ac- 

 cord with and capable of affording an adequate explanation 

 of all the known facts of the case. The theory my investi- 

 gations have led me to hold may be stated as follows: that 

 consumption is the direct result of the reduction of the 

 breathing surface of the lungs below a certain point in pro- 

 portion to the remainder of the body, and is solely produced 

 by conditions that tend to reduce the breathing capacity. 



I have experimentally produced consumption by these 

 'conditions. On one occasion I took a well-developed chest, 

 and gradually submitted it to conditions that tend to reduce 

 the breathing capacity, and at the same time, so far as pos- 

 sible, placed impediments to the performance of compensa- 

 tory action by other organs. At first there was a reduction 

 of the chest-girth, a wasting of the muscles, a loss of the 

 range of extension, the well-known change in shape, and 

 increased frequency of breathing. This was soon associated 

 with catarrh, pain in the chest, steady loss of weight, and 

 hectic; and the process was continued until I was satisfied 

 that consumption was well established. Then I induced 

 compensatory action by other organs, and submitted the 

 lungs to conditions that tended to develop them. This was 

 followed by great relief in the chest symptoms, which even 

 tually c6mpletely disappeared, by a restoration of the gen- 

 eral health, a return to tlTe normal weight, a change in the 



Klein. 



Pollock, Cotton Andrew. 



Spina, Sir Andrew Clark. 

 Pollock. 



