During his preceding journeys in the Kalmuk steppes, Metchnikoff had often heard it said that tuberculosis was almost unknown there, but that the Kalmuks took it very easily when brought into contact with foreigners. As all means of combating this disease had hitherto given very unsatisfactory results, Metchnikoff thought that researches should be started along a new path. He had long thought that observations on the extreme liability of Kalmuks to tuberculosis might perhaps provide some new data. But the study of the question necessitated a very distant journey which he now at last had the opportunity of realising.
According to Metchnikoff’s hypothesis, a natural vaccination takes place among us against tuberculosis which would explain the resistance of the majority of human beings in spite of the enormous diffusion of the disease. He concluded that some attenuated breeds of microbes become introduced into our organism during our childhood, thus vaccinating us against the virulent tuberculous bacillus. This supposition seemed to him plausible, for he had long ago found that some micro-organisms (Cienkovsky’s bacillus, the cholera bacillus, etc.) become modified in different environment and conditions, both in form and in virulence. He had described this phenomenon in 1888 in a memoir entitled Pleomorphism of Microbes. His hypothesis would explain the liability of the Kalmuks, since, if no tuberculous bacilli existed in the steppes, the inhabitants could not acquire a natural vaccination. When placed in an environment which was not free from tuberculosis, they became infected very easily, being in no wise prepared for the struggle against the virus.
The expedition to the Kalmuk country was therefore planned in order to ascertain whether tuberculosis was really absent from the steppes. This could easily be done by Pirquet’s test,[27] which at the same time would show whether the number of Kalmuks infected increased from the centre to the outer limit of the steppes and corresponded with the greater degree of contact with the surrounding population. If the enquiry confirmed the hypothesis, there would remain to be seen which microbes might best be used as vaccines.
The expedition was also intended to elucidate a few questions on the etiology of endemic plague in the Kirghiz steppes. When this intention became known, the Russian authorities desired to add to it a local mission on the study of plague epidemics in the steppes. Metchnikoff, who was chiefly concerned with the question of tuberculosis, was only able to draw up a plan of work for the Russian mission and to start it going in one of the plague centres.
The Pasteur Institute expeditionary party comprised, besides Metchnikoff, MM. Burnet, Salimbeni, and Iamanouchi. They were joined at Moscow by Drs. Tarassevitch and Choukevitch, and at Astrakhan by the physicians of the Russian plague mission. The Institut Pasteur party left Paris on May 14, 1911, full of spirits; Metchnikoff, eager to make the journey pleasant for his companions, was doing the honours of his country to the best of his ability; he fully succeeded, owing to the warm welcome and liberal hospitality which they received in Russia, where every one tried to contribute not only to the success of the expedition but to the comfort and pleasure of its members. The latter, indeed, preserved a most pleasant recollection of this journey, and, in later years, always spoke of it with pleasure.
Navigation on the Volga from Nijni Novgorod to Astrakhan was full of peculiar charm. That five days’ journey was one of the rare periods of complete rest in Metchnikoff’s life. He indulged in the dolce far niente as he watched the peaceful landscape on the passing banks. The Volga, then in flood, covered immense spaces. Here and there, whole forests emerged from the river which reflected them as in an enchanted dream. From time to time, little isolated villages appeared with the gilt cupola of a church or a monastery, then meadows, forests, steep cliffs, or gentle slopes down to the river. What poetry, what grandeur in simplicity! As in a kaleidoscope, types of varied populations and pictures of local customs followed upon each other.
Along the banks now and then were seen processions of pilgrims. Their humble, gray, stooping figures breathed deep faith and resignation. Sometimes popular songs arose from the Volga, sad, expressive, soul-penetrating chants.
This contemplative quietude was only interrupted by stations in the ports of large towns where deputations of the educated inhabitants came to wish the mission welcome. These functions had a cordial and touching character, for it was obvious that such enthusiastic demonstrations had for their source a sincere cult for the knowledge whose representatives were being fêted; it was touching to see such a living ideal in this distant and oppressed land.
At Tsaritsine, several Kirghiz embarked on our boat in order to go to a large fair which the inhabitants of the steppes attended in numbers. Metchnikoff thought this was a unique opportunity to learn whether there were any carriers of the plague bacillus among those many natives coming from all parts of the steppes. He therefore decided that those members of the expedition who had come to study plague would go to the fair with the Kirghiz, whilst he, with the rest of the expedition, would make observations on the Kalmuks of the Astrakhan region.
A most hospitable welcome awaited us there; people vied with each other in their efforts to assist the expedition. The Governor-General of Astrakhan had ordered all preparations to be made, and the mission was provided not only with necessaries but with comforts which did much to alleviate the fatigue of the long journey.