The philosopher next tried his established method of domesticating, or attenuating, the poison. The spinal cord of a rabid dog was obtained, and with this the first rabbit was inoculated. In about two weeks it took hydrophobia. Hereupon the spinal cord was extracted, and the second rabbit was inoculated; then the third; then the fourth, and so on. It was observed, however, that at each stage the intensity of the disease was in this way strangely increased; but the period of inoculation became shorter and shorter.
It was next found that by preserving the spinal cords of the animals that had died of the disease—by preserving them in dry tubes—the poison gradually lost its power. At last the virus seemed to die altogether. Then the experiment of inoculating against the disease was begun. A dog was first inoculated with dead virus. No result followed. Then he was inoculated with stale virus, and then with other virus not so stale. It was found that by continuing this process the animal might be rendered wholly insusceptible to the disease.
The next step was the human stage of experimentation. It was in July of 1885 that Pasteur first employed his method on a human subject. A boy had been bitten and lacerated by a rabid dog. The inoculation was thought to prove successful. Soon afterward some bitten children were taken from the United States to Paris, and were treated against the expected appearance of hydrophobia. Others came from different parts of the continent. Within fourteen months more than two thousand five hundred subjects were treated, and it is claimed that the mortality from hydrophobia was reduced to a small per cent of what it had been before.
It should be said, however, that neither have the results arrived at by Pasteur respecting the character of rabies been so clear, nor have his experiments on subjects supposed to be poisoned with the disease been so successful as in the case of other maladies. It remains, nevertheless, to award to Louis Pasteur the first rank among the bacteriologists of our day, as well as a first place among the philanthropists of the century. Only Robert Koch, of Germany, is to be classed in the same list with him.
KOCH'S BATTLE WITH THE INVISIBLE ENEMY.
There was a great negative reason for the success of the World's Columbian Exposition. The cholera did not come! It is quite true that there is no if in history; but if the cholera had come, if the plague had broken out in our imperial Chicago, what would have become of the Columbian Exposition? Certainly the Man of Genoa would have had to seek elsewhere for a great international gathering in his honor.
The cholera did not arrive, although it was expected. The antecedent conditions of its coming were all present; but it came not. The American millions discerned that the dreaded plague was at bay; a feeling of security and confidence prevailed; the summer of 1893 went by, and not a single case of Asiatic cholera appeared west of the Alleghenies. We are not sure that a single case appeared on the mainland of North America. And why not?
It was because the increasing knowledge of mankind, reinforced with philanthropy and courage, had drawn a line north and south across Western Europe, and had said, Thus far and no farther. Indeed, there were several lines drawn. The movement of cholera westward from the Orient began to be obstructed even before it reached Germany. It was obstructed in Italy. It was obstructed seriously on the meridian of the Rhine. It was obstructed almost finally at the meridian of London. It was completely and gloriously obstructed at the harbor of New York.