HOPES OF EXPERIMENTAL PHYSIOLOGY.

Auckland Star, Volume XXIII, Issue 4278, 9 February 1884, Page 6 (Supplement)

HOPES OF EXPERIMENTAL PHYSIOLOGY.

(By Professor Tyndall.]

The course of true science, like that of true love, never did run smooth. Oppositions are encountered and overcome, each period of retardation being followed by more than the normal rapidity of advance. In the early part of the present century thia was strikingly illustrated in regard to the undulatory theory of light, and it has been illustrated in our day by tho fortunes «f the theory of evolution. Both theories ■were pushed back for a time; both conquered ; the period of resistance being tally atoned for by the subsequent period of acceleration. It is profoundly interesting to observe the illustrations of this modo of scientific progress now going forward. A few years ago the genii theory of communicable disease was held by only a few of the bolder and more penetrative minds. It bow overspreads tho entire field of medical thought and action. We cannot take up a journal in which the etiology of disoaso is handled without being confronted by this theory ; and the more it is, considered, the more thoroughly is it seen to account for and reconcile the facts of clinical observatio jmti tho surer is the

ht which it sheds upon the work of the ysician and sanitarian. One of the most traordinary and unaccountable exporiccs in medicine was the immunity jured by a single attack of communicable sease against future attacks of the same ilady. Small-pox, typhoid, or scarlatina, r example, was found, as a general rule, occur only once in the lifetime of the invidual, the successful passage through the sorder apparently rendering the body vulnerable. From time to time during s long and valuable life I was honoured by immunications from the late Sir Thomas ratson. Knowing the profound interest I It in questions of medical theory, and vare of my leaning towards the germ leory of contagious disease, he once asked ie how I supposed the immunity just reirred to was to be accounted for. I iknowledged the difficulty, but stated at ie same time that the germ theory came earestto a satisfactory solution. A certain mount of mineral matter was known to be ecessary to the constitution of a tree. Vithout it the tree could not grow, lthough, in comparison with the other onstituenta of the wood, its quantity might ■c infinitesimal. The exhaustion of a soil ften meant the removal from it of a minute >ut necessary constituent. Reasoning from nalogy, I ventured to express the opinion hat the rarity of second attacks of comQUr.icablc ilise'iSu vs- <"l\ia to tho removal rom the system, by the first parasitic crop, if some ingredient nuessary to the growth md propagation of 111 l parasite. The cultivation of micro-organisms, vhich is now everywhere carried on, mables us to realise the smallness of the :hange which in many cases suffices to concert a highly nutritive liquid into one in•.apable of supporting microscopic life. Various important essays bearing upon this mbject have been recently published in the ' Revue Scientifique." M. Bouley there Iraws attention to the results obtained by VI. Raulin in the cultivation of the microicopic plant named Aspergillus niger The )mission of potash from Raulin's liquid mffices to make the produce fall to one-;wenty-fifth of the amount collected when ;he potash is present. The addition of an jifinitesimal amount of a substance nimical to the life of a plant is attended with still more striking results. For example, one part in sixteen hundred thousand of nitrate of silver added to the liquid sntirely stops the growth of the plant. And now we come to the important application of this fact, which has been indicated by M. Duclaux. Supposing the aspergillus to be a human parasite—a living contagium— capable of self-multiplication in the human blood, and of so altering the constitution of that liquid as to produce death ; then, the introduction into the blood of a man weighing sixty kilogrammes of five milligrammes of the nitrate of silver would ensure, if not the total effacement of this contagium, at all events the neutralisation of its power to destroy life. An index linger here points out to us the direction which physiological experiment is likely to take in the future In anticipation of the assault of infective organisms, the experimenter will try to introduce into the body substances which, though small in amount, shall so affect the blood and tissues as to render them unfit for the developement of the contagium. And subsequent to the assault of the parasite he will seek to introduce substances which shall effectually stop its multiplication. There are the strongest grounds for hope that in the case of infective diseases generally such protective substances will be found. It is, indeed, confidently asserted that such substances have been found. Dr. Polli, of Milan, for example, who has long experimented on this subject, finds that alkaline sulphides, introduced into the body, act powerfully on the contagia of marsh fever, typhoid, miliary fever, puerperal fever, and small-pox. In cases of pus-infection, these sulphides have been found particularly efficacious. >7cver was greater ardour shown in medico-physiologi-cal research than at the present moment ; and this very ardour renders it incumbent on the experimonter to keep his wishes and expectations under strong control ;it also hints at the necessity of caution in accepting alleged discoveries. But, as M. Bouley justly remarks, if Dr. Polli is correct in his facts, his results must be unspeakably important to humanity. For they would furnish the proof that it is possible, by the use of special agents, to place the human body in a condition incompatible with the existencs of contagious organisms. By the researches of Crudeli and Klebs, the deadly malaria of the Campayna was proved to be of parasitic origin ; and Grudeli is now engaged on experiment?, planned on the largest scale, with the view of discovering the means of defence against this formidable enemy. He is a member of the Italian Parliament, and is liberally ; assisted in his work by the Government of his country. His experiments thus far have been made upon the employes engaged upon railways which traverse various intensely malarial region*. Arsenic is the substance which ho has chosen to defend them from attack. He incorporates this substance in gelatine, formed into little squares, each square containing two milligrammes of arsenic ; and he begins by administering to each porson a singlo square per day. The dose is gradually augmented until it reaches S milligrammes daily. The result thus far is that out of 455 individuals treated in this way 33S were either cured of the fever or preserved from attack, while the negativa a'ld doubtful results were, in part, to be accounted for by the want of confidence on the part of the employes, and their consequent neglect of the means intended for their protection. In other places similar experiments have bcea made with satisfactory results. While cautiously holding the final judgment in reserve, it is impossible to read these reports without entertaining tho hope that theday is not far distant when the knowledge yiolded by strict scientific inquiry will enable us to sweep these parasitic diseases from the face of the earth. But to attain this end one condition is absolutely necessary, which must be stated here without disguise. The most direct and obvious way of ascertaining whether the human body can, in the way indicated, be protected from the attacks of malaria would be to take two individuals —or, better still two groups of individuals —and, having defended one group with arsenic and left tho other undefended to inoculate both groups with the malarial poison, and watch the result. It is needless to say that the man who would venture upon such an experiment would be execrated as a murderer; for assuredly some of his subjects would succumb to tho test. Is nothing, then to be done ? Is this deadly malady—and it is only one of a number of deadly maladies —to be suffered to continue its ravages without let or hindrance t Why is it that Koch, in his recont experiments in Alexandria —experiments, be it noted, conducted at the risk of his own life, and of the lives of his assistants —attached so much .importance to the power of communicating cholera to the lower animals? It is simply because he knew that once thus communicated, a way would bo open to him of combating the peat—of devising means to fortify the animal body in anticipation of attack, and to destroy its invaders after the attack had begun. Until this has been accomplished ~no sure progress can be made to-

wards the complete extirpation of cholera. In the case of malaria, fortunately, the disease is communicable to bovine animals, and more especially to those unacclimatised to its action. Thanks to the liberal funds placed at his dispasal, M. Crudeli is enabled to collect a large number of animals assailable by the disorder. He purposes dividing these animals into two groups ; to treat one group with arsenic, and to leave the other without treatment, and then to determine, once for all, by inoculation experiments, whether arsenic really possesses the power which his researches seem to haVe assigned to it. I appeal not to the partisans of either side, but to the common sense of England, whether, in the interests of humanity, the proposed experiment is not a legitimate one. lam neither a viviBectionist nor an an anti-vivisectionist, and cruelty to animals is abhorrent to my nature. I have approached this subject with a desire to weigh the pros and cons connected with it, to estimate the evil in comparison with the good; and the result of experiment, reading, and reflection leads in my case to the conclusion that they who oppose investigations such as those here indicated are unwittingly ranging themselves on the side of the enemies of the human race.