LOUIS PASTEUR.

Otago Witness, Issue 1784, 30 January 1886, Page 25

LOUIS PASTEUR.

On the fagade of a little house in the Rue dcs Tanneurs at Dole may be seen a plate bearing, in letters of gold, tho following inscription : " Here was born Louis Pasteur, December 27, 1822." It was placed there in the presence of the living man, as he was borne in a triumphal procession along the streets of the old town where he had spent his early days. " England lias ceased to stone and burn her prophets," says Froude in his Life of Carlyle; "she is contented to pay them some moderate homage, and leaves the final decorating work to future generations.'' In Germany and France, the final decorating work is less grudgingly awarded. The crowns with oak leaves are not only given to actors and prima donnas, and still less to politicians, but they are worn by men of science, to whom the word " success " bears a different meaning from that which is commonly given to it amongst ourselves : with them, success does not mean money or fame ; it means the attainment of that knowledge which shall be of lasting benefit to humanity. / Pasteur's parents were of humble origin, and poor. His father, an old soldier, decorated on the field of battle, took up the trade of a tanner when, the war over, he returned to France, and was obliged to work very hard to keep the wolf from the door. Nevertheless, he found time every evening to superintend the lessons of his son, who at an early age was sent to college, and of whom he was determined to make an. educated man. The boy, however, was no infant prodigy ; and it is reported of him that he did not always take the shortest road either to or from hchool. He was fonder of drawing than anything else, and whenever he could escape from his books would amuse himself by taking portraits of his neighbours. An old lady at Arbois wiis beard to regret, as time went on, this wasted tulent, and to say : " What a pity he should hav<> buried himself in chemistry, for he minht have made his fortune as a painter !" In due time, however, the passion for work, afterwards imperative, was born within him. He left Arbois for Besangon, and there received the degree of Bachelor dcs Lettres. He was immediately appointed tutor in bhe same college, and in the intervals of his duties he followed the course of ma thematics necessary to prepare him for the scientific examinations of the Ecole Xuniialo. Tlii re. ;it the first examination, he r ouitioiiii" i-it tLi: !i;.t. But this did not satisfy him : he began a new year of preparation, settling himself to work in a silent corner of Paiis. lie. then came out fourth ; and in 1843 he wfii en'nbled, in the great school where he whs desrined to take so distinguished a place, to follow out to his heart's content his passion for chemistry. At this time two professors, as different as possible both in manner and system of teaching, exercised an equal influence over their pupils, Dumas, at the Sorbonne, polished and grave, was accustomed to dwell on general principles ; Balavd, at the Ecole Normale, vivacious and enthusiastic, overwhelmed his audience with the multitude of facts, and did not always give his words time to follow his thoughts. One day, as he was showing potash in the lecture-room to the students, he exclaimed with fervour -. " Potash — which — potash then — potash in short — which I now present to you." The rules of the Ecole Normale might well be copied in many other educational institutions ; they leave much to the student himself, who has free access to the laboratories and the library, where he may consult all the scientific journals and reviews. Presupposing the earnest purpose of the individual, this system greatly develops the spirit of research ; but to Pastetir were lacking many of the advantages enjoyed by the present day students, for, although he was made " dean " at an incredibly early age, and entrusted with the scientific studies at the Ecole Normale Superietire, he had no laboratory ; and when he petitioned the Minister of Public Instruction for one, the reply was worthy of the period when science was at a discount, when Claude Bernard lived in a small damp garret,-and Berthelot was nothing more than an assistant in the College de France. The reply was this : " There is no clause in the budget to grant you 1500 francs a year to defray the expenses of experiments." Pasteur, whoso only thought was to learn, to question, and to study, did not hesitate to establish a laboratory — a very modest one, however — at his own expense ; and there was probably born within him that scientific imagination

which has been lately somewhat mistily described as a preconceived idea. Ho was too simple to arrogate to himself any unusual or peculiar method of discovery, bnt he used to say that nothing could be done without preconceived ideas ; and Professor Tyndall, commenting on the words, insists that they are far from meaning ideas without antecedents ; using his own poetic vein, he remarks that the days are gone for ever when angels whibpered into the hearkening human ear secrets which had no roof in man's previous knowledge or experience, and that the only revelation now open to the wise arises from " intending the mind " on acquired knowledge. At the time when Pasteur undertook his investigations on the diseases of silkworms, he had never seen a silkworm ; but the preconceived ideas he brought to bear upon the subject were the vintage of garnered facts'. . ' Remaining as Ballard's assistant at the Ecole Normale, although he had been offered the Professorship of Physics in the Lycee of Tournon,.Pasteur began the study of crystals ; and the manner in which he — still so young a student — explained away the difficulties which had appeared insurmountable to the great investigator Mitscherlich, immediately attracted the attention of the Academy. When, some time later, Biot brought the inquirers together, Mitscheylich said: 'I had studied with so much care and perseverance, in the smallest details, the two palts which formed the subject of my note to tlie .Academy, that if you have established what I .was enabled to discover, you must have been'_been guided to your result by a preconceived idea.' And this was absolutely the case, for the result was reached by simple common sense ; and the wonder is, not that a searcher of such.penetration as Pasteur should have discovered a difference in the facets of otherwise analogous crystals, bnt that an investigator so powerful and so experineced as Mitscherlich should have missed it. But besides the discovery that certain crystals supposed to be identical J~are not really so, Pasteur went on to further and exceedingly curious conclusions. He satisfied himself of the distinction between minerals or artificial products and the products which are extracted from vegetables. Such conclusions — supported, it is needless to say, by the most careful experiments — are sure to arrest the attention of a large class of people, who, dreading materialism, are ready to welcome any generalisation which separates the living from the inanimate world ; and even should they be considered somewhat insecure, the studies from which they were drawn' are known to be sound, and must endure for ever, however theory may change and inference fade away. Pasteur was now led by force of circumstauces to relinquish a line of research which still possesses for him an invincible attraction. By a sudden turn, he was thrown unexpectedly upon the subject of fermentation ; and fermentation led to the study of diseases ; but he still laments that he never had time to retrace his steps. At the time when Pasteur was nomimated dean of the Faculty of Sciences at Lille, fermentation was but little understood. The yeast-plant had been discovered ; and a German manufacturer of chemicals had noticed that common commercial tartrate of lime fermented on being dissolved and exposed to a moderate heat. His solution, he described, which was at first limpid and pure, became turbid, aud this was owing to the multiplication of a microscopic organism. Pasteur redognised in this little organism a living ferment, and became assured that ferments are in all cases living things; the substances formerly regarded as ferments being in reality the food of ferments. But whence come thfese minute organisms ? It was impossible for Pasteur to accept the theory of spontaneous generation, so enthusiastically supported by Ponchet and others. One by one he explained the fallible nature of their experiments, aud proved, by his own, that not a single circumstance had yet appeared to justify the assertion that microscopic organisms come into the world without germs or without parents like themselves. He speedily brought the most scientific men to his own conclusions. M. Fleurens, permanent secretary of the Academy of Science, delivered his opinion before the whole Academy in the following words : "As long as my opinion was not formed, I had nothing to say; now it is formed, and I can speak. The experiments are decisive. If spontaneous generation be a fact, what is necessary for the production of animalcula ? Air and putrescible liquids. Now, Pasteur puts air and putrescible liquids together, and nothing is produced. Spontaneous generation, then, has no existence. Those who still doubt; have failed to grasp tho question." Pasteur had now the key to many problerris. He traced all the maladies of wine to a specific organism which acted as a ferment, and couM be destroyed at a temperature of one hundred and twenty-two degrees Fahrenheit without injury to the wine. It was the same thing with beer ; the causes of deterioration are identically the same ; and the heating of bottled beer as a m«*an- of preservation is now largely practised, t'^pn'-lally in Europe and in America. Pasteur'd next investigations were directed tw tho diseases of silkworms. In the year 1549, an epidemic threatened to destroy the whole silkworm commerce of France. The symptoms were variable, and would break out sometime s in the egirs, sometimes in the " worms," sometimes during the processes of moulting. Innumerable remedies were tried without success, and the cultivators were iv despair. Pasteur was persuaded to leave for a time the experiments which had been so fruitful, and to advance with hesitation on an unknown road ; but the misery of the population of certain departments in the south of France decided him to accept the offer made him by his old master Dumas, who had been nominated Reporter of the Commission set on foot to determine the best means of combating tho epidemic. Pasteur started for Alais, where the plague was raging, and had not been there many hours when he was able to show to several . members of the Agricultural Committee some infinitely 'small bodies in certain worms. He found them in the eggs, the worms, and the moths ; but, curiously enough, not always in those which showed signs of disease. Other observers had already suggested a possible connection between the malady aud these little bodies, but had failed to follow out the investigation. Pasteur affirmed that here was the disease, and— twenty days after his arrival— that it was only in the moths that search should bu made for them ; that the germ of the malady might be present in the eggs and escape detection ; in the worm also it might elude microscopic examination; but that in the moth it reached a development so distinct as to render the recognition immediate. From healthy moth?, healthy eggs were sure to spring; front healthy oggs, healthy worms; from healthy worms, fine cocoons ; so that thu problem of restoration to France of its silk husbandry reduced itself to the separation of the healthy from the unhealthy moths, the rejection of the latter, and the exclusive employment of thu eggs of the former. This was the cubstance of the note which Pasteur presented to the Com-

mittee of Alais. He soon settled the question of contagion, upon which opinions were much divided. He gave healthy worms leaves over which infected worms had passed, and found by this means he could communicate the disease to as many worms as he chose. It therefore became no longer possible to doubb that pebrine was a contagious disease. The simple method by which Pasteur insured the cultivator against a recurrence of the epidemic i.« now universally adopted. As soon as her eggs aro laid the moth is crushed in a mortar and mixed with a little water ; the mixture is examined, by the microscope, and should a germ of the disease be found the eggs are immediately destroyed, with everything belonging to them. Workshops are met with everywhere at the time of tho cultivation, in which women and young girls are steadily employed, under strict supervision, in pounding and examining the moths, setting aside those eggs which are perfectly healthy, and destroying the rest. Pasteur returned to Paris crowned with success; bi'.t he had overtaxed his strength, and was seized with paralysis. Seeing, as he thought, tho near approach of death, he insisted upon dictating a last note on his important studios ; but the end wan not yet, and there were many more triumphs in store for him. Advancing in his discoveries on living torments, he drew nearer and nearer to a knowledge of the causes of contagious diseases ; but he rather drew back from this special inquiry. The ancient medical theory of parasites and living contagia was revived, and Pasteur's own researches on fermentation had much to do with it. He could no longer maintain the part of mere spectator, and taking up the investigations of Davaine, Rayer, and Roch, he approached the study of the terrible cattle-plague, which for so many years had eluded all research. No doubt could be entertained of the parasi tic nature of the disease, to which all animals were subject excepting birds. And here Pasteur stepped in with what Tyndall calls a " hand specimen" of his genius. The temperature which prohibits the multiplication of the poisonous parasite is forty-four degrees ; the temperature of the blood of birds forty-two degrees — it is therefore close upon that which destroys infection, aud might well be the cause of their immunity. Pasteur then made tho following experiment. He placed the feet of a fowl in cold water, thereby considerably lowering the temperature. He then inoculated it, and in four-and-twenty hours it was dead. The argument was clinched by inoculating a chilled fowl, allowing the fever to come to a head, and then removing the patient, wrapped in cotton-wool, to a warm chamber, where it rapidly recovered; proving that the career of the parasite was brought to an end. The experiment is conclusive, and is full of suggestiveness as regards the treatment of fever in man. The next step was the consequence of long dwelling on the mystery of vaccination. Since most diseases are in thoir nature nonrecurrent, why should there not, he argued, be found for each of them a preventative disease, which, being similar, but not so virulent, should act as a safeguard ? Pasteur found that lengthened contact with free air weakens the contagion, or the microscopic parasites ; they are living things, demanding certain elements of life, as do other living things, and they so use up that which the body contains as essential to their growth, and it may be impossible to produce a second crop. Even a less vigorous parasite may suffice to exhaust the soil, and then a highly virulent one may be introduced, and will prove powerless. This is the whole secret of Jenner's discovery ; but he employed it only in a single disease, leaving the field to Pasteur, who grasped at once the nature and extent of the discovery, and applied it with results which have appeared almost miraculous. In 1881, Pasteur communicated to the Academy his discovery, that by repeated " cultivations " of a poisonous parasite, much of its virulence could be destroyed — that, in fact, it might be rendered benign ; and though much applause followed his exposition, some of his colleagues could not help suggesting that there was a little romance in the theory. The President of the Society of Agriculture at Melun invited Pasteur to make a public experiment of splenic fever vaccination. He accepted ; and May 5, 1881, an immense concourse of interested spectators assembled to watch the result. A flock of sheep was divided into two groups ; those in the one were vaccinated, those in the other were left alone. A number of cows were similarly treated. After fourteen days, all the auimals were inoculated with a virulent kind of cattle-disease; and three days subsequently, 21 sheep which had not been protected by vaccination were dead, and the remaining ones dying. The vaccinated ones had hardly suffered at all. It was the same thing with the cows. [ A burst of enthusiasm followed these marvellous results; and although every new discovery is sure to be opposed, the significant fact remains that Pasteur is overwhelmed with applications for vaccine. Pasteu* i-; now over sixty yr-ars of age, but he still continues his researches with unabated oiKsvgy ; the last have reference to the most terrible malady of all— to hydrophobia, concerning which we may have something to say by-and-bye. The immense possibilites which his discoveries are constantly revealing leave hardly any prospect too wide for fulfilment. — Chambers' Journal.