394 



NATURE 



[August 27, 189: 



(1) Is the risk lo ihe individual consumer of such a nature 

 that it can be detected and estimated? 



(2) Is it of such a nature that it can be counteracted ? 



(3) Is the collective risk to which the community is exposed 

 sufficient to demand the interference of the State ? and 



(4) If it is, How can the State interfere with effect? 



Of the two practical questions which relate respectively to in- 

 fection by milk and to infection by meat, the latter was very 

 largely discussed at a Congress on the subject of tuberculosis 

 held in Paris in 1888, and has again been discussed very re- 

 cently. In the first of these debates the medical profession did 

 not take a very prominent part. The question whether the 

 flesh of tuberculous animals is dangerous or not was regarded 

 chiefly from the point of view of the veterinarian. 



In 1888, M. Arloing, following out the principles enunciated 

 by another gifted pathologist, the late M. Toussaint, that 

 tubercle is a disease totius subslantia corporis, maintained that 

 the time had come to act "conformant a la logique." One out 

 of every six carcasses had been shown, he said, to be infective, 

 when tested by administering it to test animals as food. He 

 calculated that over one thousand persons joined in the con- 

 sumption of every such carcass, and consequently that one-sixth 

 of this number — that is, about 170 persons — -must be subjected 

 to the risk of infection for every animal sent to the shambles. 

 If this reasoning were true, if we could measure the danger to 

 the human consumer by the presence of tuberculosis among 

 animals used for food irrespectively of other considerations, then 

 M, Arloing was right in his practical deduction from it that 

 whatever interests conflict with public health they must give way. 

 It was our duty to insist on the right of science to dictate ; but in 

 doing so it was necessary to be careful not to do so until the 

 question had been looked at from all sides and the whole evidence 

 had been heard. 



In some of these discussions it had not been sufficiently con- 

 sidered that the question was not whether the consumption of 

 tuberculous meat was in itself attended with risk, but whether 

 the presence of tuberculous diseases among ourselves was in any 

 way due to the fact that we occasionally eat meat which contained 

 bacilli. It was not sufiicient to show that on the one hand there 

 was a fearful mortality from tuberculous diseases, and that on 

 the other there existed a cause to which this calamity might be 

 attributed. It must also be shown that the effect was actually 

 produced by the cause, in such sense that if the cause were re- 

 moved we might hope that the effect would disappear. 



Twenty-three years ago Chauveau fed three heifers with 

 tuberculous material from the body of a cow and obtained posi- 

 tive results. At that time the idea that tuberculosis was a virulent 

 disease was new. M. Villemin had made his great discovery, but 

 it had not yet been accepted, and consequently Chauveau's results 

 were severely criticized, and were the subject of much discussion, 

 which extended over several years (1868-74), during which he 

 repeated his observations, effectually silenced his opponents, 

 and determined with the greatest exactitude all the conditions 

 which are required to insure success in the experimental pro- 

 duction of tuberculosis by feeding. Gerlach about the same 

 time made similar experiments in Germany which led him to 

 advocate in the most energetic manner the restriction of the sale 

 of tuberculous meat. 



These two initial investigations were followed by many 

 others. In 1884, Baumgarten showed that a couple of ounces of 

 milk to which a pure culture of tubercle bacillus had been added 

 were sufficient to produce characteristic tuberculosis in the in- 

 testines of a rabbit ; and that the effect of such feeding was so 

 constant that by examining the animals so fed at successive 

 periods all the stages of the process could be thoroughly investi- 

 gated, the most important result being that after a period of 

 latency of a fortnight, during which no traces of infection were 

 visible, the lymphatic follicles of the mucous membrane and the 

 mesenteric glands began to enlarge simultaneously without any 

 change whatever in the intestinal epithelium. 



It was thus shown with a precision which was not before ob- 

 tainable that the initial phenomenon of tuberculosis was primarily 

 a proliferation of the adenoid tissue of the lymphatic system, and 

 that the bacillus was capable of finding its way into the lym- 

 phatic system without leaving behind it any appreciable traces of 

 its presence at the portals by which it had gained admission. 

 Since 1884 our knowledge of the subject had been still further 

 advanced by Cornil, under whose direction two very important 

 researches, confirming and extending Baumgarten's results, have 

 been recently published, from which it was evident that when 



NO. II 39, VOL. 44] 



the tubercle bacillus is absorbed from the intestine it follows the 

 course of the lacteals, and that the lesions which it produces 

 correspond closely with those which present themselves in those 

 rare instances in which it is possible to observe the first begin- 

 nings of enteric tubercle in the human subject. 



Much, however, has still to be learned by the experimental 

 method — information which could only be gained by observations 

 on animals. According to those who regard tuberculosis as 

 necessarily a disease, totius stibstantice corporis, in which every 

 part of the body is contaminated, all meat derived from the 

 body of a tuberculous animal ought to be condemned, whether it 

 appears healthy or not, for they argue that in every such 

 animal, however localized the disease may be, bacilli circulate 

 in the blood, and are so universally distributed. 



Prof. Sanderson believed that this was not true, and that 

 we are not entitled to assume that the flesh of every tuberculous 

 animal is infectious unless it be proved to be so. As against the 

 probability of its being so, it must be noted that the tubercu- 

 losis of cattle, although the product of the same bacillus as the 

 tuberculosis of man, is a disease of comparatively slow progress. 

 It localizes itself in structures which are not essential to life, and 

 nutrition might be so little interfered with that the animal could 

 be readily fattened for the market. There was no doubt that 

 the flesh of such animals might be to all appearances in good 

 condition, and might be offered for sale as meat of prime quality, 

 and as yet we have no evidence that it is infective. 



Turning from the souice of infection to its effects, from the 

 bacillus to its field of disease and death-producing action. 

 Prof. Sanderson said that tuberculous diseases contribute 

 something like 14 per cent, to the total of deaths from all causes, 

 and that during childhood, as distinguished from adult life on 

 the one hand and from infancy on the other, tuberculous mor- 

 talityjscarcely amounts to a quarter of this percentage, whereas 

 in infancy it only falls a little short of it, and in early adult life, 

 it very far exceeds it. 



There was evidence that under certain conditions the virus of 

 tubercle was absorbed by the lymphatic system from the small 

 intestine in man, and that when this happens it may give rise to 

 lesions of the same nature as those produced in animals by the 

 injection of liquids in which bacilli are suspended — that is, to 

 lesions which originate in the lymphatic system. Tuberculous 

 disease of the intestinal mucous membrane, although very com- 

 mon, never occurred in the adult and very rarely in infancy as a 

 primary disease. In the adult it might occur as an ulterior con- 

 sequence of pulmonary consumption, the way in which it oc- 

 curred being very evident. In the advanced stages of that 

 disease muco-purulent liquid was discharged in quantity from 

 the softened parts. This material charged with virulent bacilli 

 might infect the mucous membrane along which it passed so that 

 it is easy to distinguish bronchi which lead from vomicae by the 

 tuberculous nodules with which they are more or less beset. In 

 advanced phthisis the sputum is so abundant that a. certain pro- 

 portion of it is from time to time swallowed. No effect is pro- 

 duced in the oesophagus or stomach, for along the former it 

 passes too rapidly, while in the latter the mucous membrane is 

 effectually protected by the gastric juice, which, although incap- 

 able of devitalizing the bacillus of tubercle, arrests its develop- 

 ment. In the alkaline contents of the small intestine a condition 

 more favourable to its development was found, and from 

 there it was absorbed, just as any other particle of similar size 

 might be, by the lymphatic follicles. Tuberculous disease of the 

 small intestine in the adult thus occurred. It v\as always a 

 secondary result of pulmonary phthsis. 



In childhood the case is different. Tuberculosis does not 

 begin to assert itself as a cause of death until the third month 

 of extra uterine life, but after this there was good reason for sup- 

 posing that the bacillus plays an important part as a cause of 

 mortality. 



To the pathologist the question of how latent tuberculosis of 

 the lymphatic system or of bone originates, i.e. how the bacilli 

 which produce them are introduced into the blood stream was 

 one of great interest. Prof. Sanderson confessed it to be his 

 belief that in a certain proportion of cases the cryptogenetic 

 tuberculoses were due to causes which operate before birth. 

 From Dr. Muller's Munich statistics it might be gathered that 

 in less than half of the cases in which the lymphatic glands are 

 found to be tuberculous the affection has its seat in the mesentery, 

 and that the mucous membrane of the intestine is tuberculous in 

 a still smaller proportion— less than a quarter. In many of 

 these cases the mucous membrane was no doubt affected subse- 



