Pasteur was, after this, asked to give a lecture on splenic fever in the large hall of the Pouilly farm. Then, in clear, simple language, meeting every objection half-way, showing no astonishment at ignorance or prejudice, knowing perfectly well that many were really hoping for a failure, he methodically described the road already travelled, and pointed to the goal he would reach. For nearly an hour he interested and instructed his mixed audience; he made them feel the genuineness of his faith, and, besides his interest in the scientific problem, his desire to spare heavy losses to cultivators. After the lecture, some, better informed than others, were admiring the logical harmony of that career, mingling with pure science results of incalculable benefit to the public, an extraordinary alliance which gave a special moral physiognomy to this man of prodigious labours.
An appointment was made for the second inoculation. In the interval—on May 6, 7, 8 and 9—Messrs. Chamberland and Roux came to Pouilly le Fort to take the temperature of the vaccinated animals, and found nothing abnormal. On May 17 a second inoculation was made with a liquid which, though still attenuated, was more virulent than the first. If that liquid had been inoculated to begin with it would have caused a mortality of 50 per 100.
“On Tuesday, May 31,” wrote Pasteur to his son-in-law, “the third and last inoculation will take place—this time with fifty sheep and ten cows. I feel great confidence—for the two first, on the 5th and the 17th, have been effected under the best conditions without any mortality amongst the twenty-five vaccinated subjects. On June 5 at latest the final result will be known, and should be twenty-five survivors out of twenty-five vaccinated, and six cows. If the success is complete, this will be one of the finest examples of applied science in this century, consecrating one of the greatest and most fruitful discoveries.”
This great experiment did not hinder other studies being pursued in the laboratory. The very day of the second inoculation at Pouilly le Fort, Mme. Pasteur wrote to her daughter, “One of the laboratory dogs seems to be sickening for hydrophobia; it seems that that would be very lucky, in view of the interesting experiment it would provide.”
On May 25, another letter from Mme. Pasteur shows how deeply each member of the family shared Pasteur’s preoccupations and hopes and was carried away with the stream of his ideas: “Your father has just brought great news from the laboratory. The new dog which was trephined and inoculated with hydrophobia died last night after nineteen days’ incubation only. The disease manifested itself on the fourteenth day, and this morning the same dog was used for the trephining of a fresh dog, which was done by Roux with unrivalled skill. All this means that we shall have as many mad dogs as will be required for experiments, and those experiments will become extremely interesting.
“Next month one of the master’s delegates will go to the south of France to study the ‘rouget’ of swine, which ordinarily rages at this time.
“It is much hoped that the vaccine of that disease will be found.”
The trephining of that dog had much disturbed Pasteur. He, who was described in certain anti-vivisectionist quarters as a laboratory executioner, had a great horror of inflicting suffering on any animal.
“He could assist without too much effort,” writes M. Roux, “at a simple operation such as a subcutaneous inoculation, and even then, if the animal screamed at all, Pasteur was immediately filled with compassion, and tried to comfort and encourage the victim, in a way which would have seemed ludicrous if it had not been touching. The thought of having a dog’s cranium perforated was very disagreeable to him; he very much wished that the experiment should take place, and yet he feared to see it begun. I performed it one day when he was out. The next day, as I was telling him that the intercranial inoculation had presented no difficulty, he began pitying the dog. ‘Poor thing! His brain is no doubt injured, he must be paralysed!’ I did not answer, but went to fetch the dog, whom I brought into the laboratory. Pasteur was not fond of dogs, but when he saw this one, full of life, curiously investigating every part of the laboratory, he showed the keenest pleasure, and spoke to the dog in the most affectionate manner. Pasteur was infinitely grateful to this dog for having borne trephining so well, thus lessening his scruples for future trephining.”
As the day was approaching for the last experiments at Pouilly le Fort, excitement was increasing in the veterinary world. Every chance meeting led to a discussion; some prudent men said “Wait.” Those that believed were still few in number.