Page:George Archdall Reid 1896 The present evolution of man.djvu/228



is, however, an objection to the phagocytic theory of acquired immunity, which at first sight appears fatal, but which I think is capable of being overcome. Pasteur found that in a man bitten by a rabid animal, the onset of hydrophobia, or at any rate its fatal termination, could in a great proportion of cases be prevented by injecting into the tissues of the patient emulsions made from the spinal cords of animals dead of that disease, beginning with an emulsion from a cord that had been dried for fifteen days in a closed vessel over caustic potash, whereby it was in a great measure bereft of moisture, and the pathogenic organisms were probably quite destroyed, continuing day by day with emulsions from cords of animals more and more recently dead, from which, therefore, the moisture was less and less thoroughly abstracted, and in which the pathogenic life was less and less completely destroyed, and ending with a cord which was absolutely fresh and therefore virulently infective, as could be proved by inoculating a susceptible animal with it and producing fatal disease. It is to be presumed that the pathogenic organisms were absent or almost absent from the first injected, the old and thoroughly dried cord, but that their toxins were jn'esent in it, and that in the fresher cords, in direct proportion to their freshness, the organisms were present as well as their toxins.