a history of science-4-第40节
按键盘上方向键 ← 或 → 可快速上下翻页，按键盘上的 Enter 键可回到本书目录页，按键盘上方向键 ↑ 可回到本页顶部！
————未阅读完？加入书签已便下次继续阅读！
t re…enters the flask will thus come into contact with the heated glass and the heated liquid； so as to destroy the vitality of any dust germs that may exist in the air。 The air itself will re…enter very gradually； and slowly enough to enable any dust to be taken up by the drop of water which the air forces up the curvature of the tube。 Ultimately the tube will be dry； but the re…entering of the air will be so slow that the particles of dust will fall upon the sides of the tube。 The experiments show that with this kind of vessel； allowing free communication with the air； and the dust not being allowed to enter； the dust will not enter at all events for a period of ten or twelve years； which has been the longest period devoted to these trials； and the liquid； if it were naturally limpid； will not be in the least polluted neither on its surface nor in its mass； although the outside of the flask may become thickly coated with dust。 This is a most irrefutable proof of the impossibility of dust getting inside the flask。
〃The wort thus prepared remains uncontaminated indefinitely； in spite of its susceptibility to change when exposed to the air under conditions which allow it to gather the dusty particles which float in the atmosphere。 It is the same in the case of urine； beef…tea； and grape…must； and generally with all those putrefactable and fermentable liquids which have the property when heated to boiling…point of destroying the vitality of dust germs。〃＇7＇
There was nothing in these studies bearing directly upon the question of animal diseases； yet before they were finished they had stimulated progress in more than one field of pathology。 At the very outset they sufficed to start afresh the inquiry as to the role played by micro…organisms in disease。 In particular they led the French physician Devaine to return to some interrupted studies which he had made ten years before in reference to the animal disease called anthrax； or splenic fever； a disease that cost the farmers of Europe millions of francs annually through loss of sheep and cattle。 In 1850 Devaine had seen multitudes of bacteria in the blood of animals who had died of anthrax； but he did not at that time think of them as having a causal relation to the disease。 Now； however； in 1863； stimulated by Pasteur's new revelations regarding the power of bacteria； he returned to the subject； and soon became convinced； through experiments by means of inoculation； that the microscopic organisms he had discovered were the veritable and the sole cause of the infectious disease anthrax。
The publication of this belief in 1863 aroused a furor of controversy。 That a microscopic vegetable could cause a virulent systemic disease was an idea altogether too startling to be accepted in a day； and the generality of biologists and physicians demanded more convincing proofs than Devaine as yet was able to offer。
Naturally a host of other investigators all over the world entered the field。 Foremost among these was the German Dr。 Robert Koch； who soon corroborated all that Devaine had observed； and carried the experiments further in the direction of the cultivation of successive generations of the bacteria in artificial media； inoculations being made from such pure cultures of the eighth generation； with the astonishing result that animals thus inoculated succumbed to the disease。
Such experiments seem demonstrative； yet the world was unconvinced； and in 1876； while the controversy was still at its height； Pasteur was prevailed upon to take the matter in hand。 The great chemist was becoming more and more exclusively a biologist as the years passed； and in recent years his famous studies of the silk…worm diseases； which he proved due to bacterial infection； and of the question of spontaneous generation； had given him unequalled resources in microscopical technique。 And so when； with the aid of his laboratory associates Duclaux and Chamberland and Roux； he took up the mooted anthrax question the scientific world awaited the issue with bated breath。 And when； in 1877； Pasteur was ready to report on his studies of anthrax； he came forward with such a wealth of demonstrative experimentsexperiments the rigid accuracy of which no one would for a moment think of questioninggoing to prove the bacterial origin of anthrax； that scepticism was at last quieted for all time to come。
Henceforth no one could doubt that the contagious disease anthrax is due exclusively to the introduction into an animal's system of a specific germa microscopic plantwhich develops there。 And no logical mind could have a reasonable doubt that what is proved true of one infectious disease would some day be proved true also of other； perhaps of all； forms of infectious maladies。
Hitherto the cause of contagion； by which certain maladies spread from individual to individual； had been a total mystery； quite unillumined by the vague terms 〃miasm；〃 〃humor；〃 〃virus；〃 and the like cloaks of ignorance。 Here and there a prophet of science； as Schwann and Henle； had guessed the secret； but guessing； in science； is far enough from knowing。 Now； for the first time； the world KNEW； and medicine had taken another gigantic stride towards the heights of exact science。
LISTER AND ANTISEPTIC SURGERY
Meantime； in a different though allied field of medicine there had been a complementary growth that led to immediate results of even more practical importance。 I mean the theory and practice of antisepsis in surgery。 This advance； like the other； came as a direct outgrowth of Pasteur's fermentation studies of alcoholic beverages； though not at the hands of Pasteur himself。 Struck by the boundless implications of Pasteur's revelations regarding the bacteria； Dr。 Joseph Lister （the present Lord Lister）； then of Glasgow； set about as early as 1860 to make a wonderful application of these ideas。 If putrefaction is always due to bacterial development； he argued； this must apply as well to living as to dead tissues； hence the putrefactive changes which occur in wounds and after operations on the human subject； from which blood…poisoning so often follows； might be absolutely prevented if the injured surfaces could be kept free from access of the germs of decay。
In the hope of accomplishing this result； Lister began experimenting with drugs that might kill the bacteria without injury to the patient； and with means to prevent further access of germs once a wound was freed from them。 How well he succeeded all the world knows； how bitterly he was antagonized for about a score of years； most of the world has already forgotten。 As early as 1867 Lister was able to publish results pointing towards success in his great project； yet so incredulous were surgeons in general that even some years later the leading surgeons on the Continent had not so much as heard of his efforts。 In 1870 the soldiers of Paris died； as of old； of hospital gangrene； and when； in 1871； the French surgeon Alphonse Guerin； stimulated by Pasteur's studies； conceived the idea of dressing wounds with cotton in the hope of keeping germs from entering them； he was quite unaware that a British contemporary had preceded him by a full decade in this effort at prevention and had made long strides towards complete success。 Lister's priority； however； and the superiority of his method； were freely admitted by the French Academy of Sciences； which in 1881 officially crowned his achievement； as the Royal Society of London had done the year before。
By this time； to be sure； as everybody knows； Lister's new methods had made their way everywhere； revolutionizing the practice of surgery and practically banishing from the earth maladies that hitherto had been the terror of the surgeon and the opprobrium of his art。 And these bedside studies； conducted in the end by thousands of men who had no knowledge of microscopy； had a large share in establishing the general belief in the causal relation that micro…organisms bear to disease； which by about the year 1880 had taken possession of the medical world。 But they did more； they brought into equal prominence the idea that； the cause of a diseased condition being known； it maybe possible as never before to grapple with and eradicate that condition。
PREVENTIVE INOCULATION
The controversy over spontaneous generation； which； thanks to Pasteur and Tyndall； had just been brought to a termination； made it clear that no bacterium need be feared where an antecedent bacterium had not found lodgment； Listerism in surgery had now shown how much might be accomplished towards preventing the access of germs to abraded surfaces of the body and destroying those that already had found lodgment there。 As yet； however； there was no inkling of a way in which a corresponding onslaught might be made upon those other germs which find their way into the animal organism by way of the mouth and the nostrils； and which； as was now clear； are the cause of those contagious diseases which； first and last； claim so large a proportion of mankind for their victims。 How such means might be found now became the anxious thought of every imaginative physician； of every working microbiologist。
As it happened； the world was not kept long in suspense。 Almost before th
