[Aldo Castellani and the expeditions of the Royal Society to the black sleep's country].

At the beginning the investigation on infectious diseases was plenty of adventures in exotic countries. The efforts of the English investigators, headed by Patrick Manson, gave birth to the "tropical" medicine and "tropical" diseases, like the sleeping sickness, which was sweeping the country north to the Victoria Lake in 1901. The Royal Society of London sent two Commissions in search of the etiological agent. Aldo Castellani was decisive for the failure of the first - Low, Castellani, Christy,1902 - because even he saw Trypanosoma in samples of some patients, he did not appreciate his discovery; and decisive also for the success of the second -Bruce, Nabarro, Greig, 1903 - when he and Bruce recognized this Trypanosoma as the etiological agent. Following these expeditions, Low developed a brilliant career in England, Christy a life of investigation mixed up with adventures through Asia and Africa and Castellani a long life of lights and shadows in many lands.