Science. CONSUMPTION.

Waikato Times, Volume XIX, Issue 1619, 18 November 1882, Page 2 (Supplement)

Science. CONSUMPTION.

By Pkoi-\ Tyndall,

On the 21th March, 1882, an address of very serious public import was delivered by Dr. Koch before the Physiological Society of Berlin. It touches a question in which we are all at present interested — that of experimental physiology — and I may, therefore, be permitted to give some account of it in the Times. The address, a copy of which has been courteously sent to me by its author, is entitled, " The Etiology of Tubercular Disease." Koch first made himself known by the penetration, skill, and thoroughness of his researches on the contagium of splenic fever. By a process of inoculation and infection, he traced this terrible parasite through all its ' stages of development, anil through its various modes of action. This masterly investigation caused the young physician to be transferred from a modest country practice, in the neighbourhood of Bieslau, to the post of Government adviser iv the Imperial Health Department of Berlin. From this department has lately issued a most important scries of investigations on the etiology of infective disorders. Koch's last inquiry deals with a disease which, in point oi mortality, stands at the head of them all. If, ho says, the .seriousness of a malady be measured by the number of its victims, then the most dreaded pests which have hitherto ravaged the woild — plague and cholera included — must stand far behind the one now under consideration. Koch makes the staifcling statement that one-seventh of the deaths of the human race aie due to tubercular disease, while fully one-thii d of those who die in active middle age are carried off by the same cause. Piior to Koch it had been 2?laced beyond doubt that the disease was communicable ; and the aim of the Berlin physician has been to determine the precise character of the contagium which previous experiments on inoculation and inhalation had proved to be capable of indefinite tiansfer .and reproduction. He subjected the diseased organs of a great number of men and animals to microscopic examination, and found, in all cases, the tubercles infested with a minute, lod-shaped paiasite, which, by means of a special dye, he diffoientiated liom the surlounding tissue. It was, he says, in the highest degree impressive to observe in the centic ot the tubeicle cell the minute organism which had created it. Transfening directly, by inoculation, ths tuberculous matter from diseased animals to healthy ones, he in every instance leproduced the disease. To meet the objection that it was not the parasite itself, but some virus in which it was embedded in the diseased organ, that was the real contagium, he cultivated his banlli artificially, for long periods of time, and through many successive generations. With a speck of matter, for example, from a tuberculous human lung, he infected a substance prcpaicd, after much trial, by himself, with the view ot affording nutriment to the paiasite. Here he permitted it to grow and multiply. From this new generation he took a minute sample, ami infected therewith fresh nutritive matter, thns producing another brood. Generation after generation of bacilh were developed in this way without the intervention of disease. At the end of the process, which sometimes embraced successive cultivations extending over half a year, the puiifiecl bacilli were introduced into the circulation of healthy animals of various lands. In every case, inoculation was followed by the reproduction and spread of the parasite, and the generation of the original disease. Permit me to give a fuither, though still biief and sketchy account of Koch's experiments. Of six guinea pigs, all in good health, four were inoculated with bacilli derived originally from a human lung, which, in fiftyfour days, had produced live successive generations. Two of six; animals were not infected. In eveiy one of the infected cases the guinea pig sickened and lost flesh. After thirty-two days one of them died, and after thiity-iive days the remaining live were killed and examined. In the guinea pig that died, and in the three remaining infected ones, strongly pionounced tubercular disease had set in. Spleen, liver, and lungs were found filled with tubercles ; while in the two uninfected animals no trace of the disease was observed. In a second experiment, six out of eight guinea pigs were inoculated with cultivated bacilli, derived originally from the tuberculous lung of a monkey, bred, and rebred for ninety-five days, until eight generations had been produced. Every one of these animals was attacked, while the two uninfected guinea pigs remained perfectly healthy. Similar experiments were made with cats, rabbits, mice, and other animals, and, without exception, it was found that the injection of the parasite into the animal system was followed by decided, and, in most cases, virulent tubercular disease. In the cases thus far mentioned, inoculation had been effected in the abdomen. The place of inoculation was afterward changed to the aqueous humour of the eye. Thiee labbits leceiveel each a speck of bacillus culture, derived originally from a human lung affected with pneumonia. Eighty-nine days had been devoted to the culture of the organism. The infected rabbits rapidly lost flesh, and after twenty-five days, were killed and examined. The lungs of eveiy one of them were found charged with tubeicles. Of thiee other rabbits, one leceived an injection of puie blood serum in the aqueous humor of the eye, while the other two were infected, in a similar way, with the same serum, containing bacilli derived originally from a diseased lung, and subjected to ninety-one clays' cultivation. After twenty-eight days, the rabbits were killed. The one which had leceived an injection of pure serum was found perfectly healthy, while the lungs of the two others were found overspread with tubercles. Other experiments are recorded in this admiiable essay, from which the weightiest practical conclusions may bo drawn. K6ch determines the limits of temperatuie between which the tubercle bacillus can develop and multiply. The minimum temperature he iinds to be 86 deg. Fahrenheit, and the maximum 104 deg, He concludes that, unlike the bacillus anthraeis of splenic fever, which can flourish freely outside the animal body, in the temperate .zone animal warmth is necessary for the propagation of the newly discovered organism. In a vast number of cases, Koch has examined the matter expectorated from the lungs of persons affected with phthisis, and found in it swarms of bacilli, while in matter expectorated from the lungs of persons not thus afflicted, he has never found the organism. The expectorated matter in , the former cases was highly infective, nor Aid-dry-ing destroy its virulence. Guinea pigs infected with expectorated matter which had been kept.dry for two, four, and eight weeks respectively, were smitten with tubercular ; disease, quite as virulent as that produced by fresh expectoration. Koch points to the grave danger of inhaling air, in which particles of the dried sputa of consumptive patients mingles with dust of other kinds. It would be mere impertinence on my part to draw the obvious moral from these experiments. In no ' other conceivable way than that pursued . by Koch could-tfie true character of the, most destructive malady, by which ihuimanity ; '"is _nbw' assailed , be determined.