of morphia causes an immediate reaction, and the animal, after remaining in a more or less dazed condition for several hours, finally succumbs to this drug. Dr. Roux is inclined to regard this difference in the susceptibility exhibited by animals to one and the same poison as being due to a good deal of the toxin, when subcutaneously introduced, failing to reach the nerve-centres, it having been destroyed or arrested in the system before it could attack them. What is the nature of the subtle forces which may so beneficially intervene between the toxin and its victim has long been a problem which has excited the interest and ingenuity of some of the most brilliant scientific authorities of the day, and it is one which, even in the hands of men like Metchnikoff, is still awaiting a satisfactory solution! The important point was next approached by Dr. Roux as to whether an animal, successfully trained to withstand large doses of the poison, as ordinarily introduced, could also resist it when directly inoculated into the brain. Is, in fact, the undoubted immunity to tetanus poison which may be possessed by an animal due to the nerve-centres having become insensible to this substance? The answer to this question would appear to be in the negative, for animals artificially protected from tetanus poison introduced under the skin succumbed to a small dose inoculated direct into the brain, which would otherwise have not produced even a slight passing tetanic affection of the limb where the inoculation was made. Immense numbers of experiments were made under varying conditions, but the result was fully confirmed, showing that the nerve-centres had not acquired any immunity to the poison, although the blood serum of the victims to such cerebral inoculations was proven over and over again to be endowed with strong protective properties against tetanus poison. The endeavour was then made to, in Dr. Roux's words, "place the anti-toxin where the toxin is working," and preserve the vital force of the nervous tissue. To arrest tetanus by substituting cerebral for subcutaneous inoculations of the anti-tetanic serum was the next feat attempted. Several guinea-pigs and rabbits were inoculated subcutaneously with virulent doses of tetanus poison sufficient to kill them in about seventy hours; some were subsequently treated with antitoxic serum introduced in the ordinary way under the skin, whilst others were inoculated with from six to seven drops of this protective serum direct into the brain. The results were extraordinarily successful. Although but a few drops of the anti toxin were used for the cerebral inoculations, the animals survived the otherwise fatal doses they had received of the toxin; whilst out of seventeen guinea-pigs which received subcutaneous inoculations of the anti-toxin only two recovered, and the quantity of the anti-toxin employed reached as much as from ten to twenty cubic centimetres in some of the experiments, contrasting in a remarkable manner with the few drops which sufficed in the case of the cerebral inoculations. Dr. Roux sums up this splendid result in the following modest words: "Il ne suffit pas de donner de l'anti-toxine, il faut la mettre au bon endroit." The significance and far-reaching application of this most important discovery cannot easily be overestimated. Hitherto the preparation of an anti-toxin has been the chief point considered, but Dr. Roux and his able coadjutor, M. A. Borrel, have shown how great may be the results which attend its method of administration, and have opened up an entirely new direction for investigation. Although the subject of immunity is not, as we have seen, by any means wholly a latter-day creation, yet its approach and consideration from a modern point of view, assisted by the resources and equipment provided by modern scientific methods, justifiably entitles the nineteenth century to claim it as its own discovery. However brilliant and successful the labours may be of those who will follow in the future, subsequent generations will know how to venerate those great leaders of scientific thought, amongst whom we must rank Pasteur, to whose genius the world owes so great a debt of gratitude, and the vast extent of whose labours cannot be adequately measured at the present day by reason of the restricted scientific horizon which encircles public opinion in this country. THE END PLYMOUTH WILLIAM BRENDON AND SON PRINTERS |