Around the same time, Germany sent an expeditionary team led by Robert Koch to investigate the epidemic in Togo and East Africa. In 1909, one of the team members, Friedrich Karl Kleine discovered that the parasite had developmental stages in the tsetse flies. Bruce, in the third Sleeping Sickness Commission (1908–1912) that included Albert Ernest Hamerton, H.R. Bateman and Frederick Percival Mackie, established the basic developmental cycle through which the trypanosome in tsetse fly must pass. An open question, noted by Bruce at this stage, was how the trypanosome finds its way to the salivary glands. Muriel Robertson, in experiments carried out between 1911 and 1912, established how ingested trypanosomes finally reach the salivary glands of the fly.
