I had to appeal to the General Governor, who ended by countermanding the Prefect's order; nevertheless this incident was not without regrettable consequences concerning the ulterior activities of the Institute. Apart from all that, a deep scission took place between the members, though they were so few, of the Institute itself, and this had fatal consequences. The men who were in charge of the practical work ceased to work in concert; I could not take their place, being overwhelmed with scientific researches, besides which, holding no medical degree, I was not qualified to perform vaccinations on human beings. Under those conditions, I understood that in my quality as a theoretician, I should do well to retire, leaving the laboratory to practitioners who, bearing full responsibility, would fill the part better. During his stay at the Odessa Bacteriological Institute, Metchnikoff had busied himself with infectious diseases in order to answer the first objections to his theory. He began by the microbes of erysipelas and showed that the phenomena of the disease, as well as those of recovery, were in full accord with the postulates of the phagocyte theory. And then he studied relapsing fever in order to answer Baumgarten's objections, affirming that there was no phagocytic reaction in that disease, though it almost invariably ended in recovery. Experiments on man not being possible, Metchnikoff procured some monkeys, which he inoculated with relapsing fever, and ascertained that Baumgarten's error was due to the fact that he had only looked for phagocytosis in the patient's blood, whilst it really took place in the spleen. These researches on erysipelas and relapsing fever were published in Virchow's _Archives_ in 1887. Besides this scientific work, he was also giving lectures on bacteriology to some physicians, and was in full productive activity when external opposition and the discord among his collaborators in the Institute itself forced upon him the conviction that he could remain there no longer. At that very moment the Prince of Oldenburg, having founded a Bacteriological Institute at Petersburg, invited Metchnikoff to take charge of it. He had to refuse, fearing the Northern climate for my health, and knowing from experience that it was impossible for a layman to manage an Institute with a medical staff. Yet he could not do without a laboratory. Seeing no possibility of having one in Russia, he decided to look abroad for a refuge and a laboratory. "Having learnt from experience at Odessa," he wrote, "how difficult was the struggle against an opposition coming from all sides and devoid of reasonable causes, I preferred to go abroad to look for a peaceful shelter for my scientific researches."