Complex sentence: These Indians provided Ross with clues in the belief that the moment Ross discovered what was to be discovered, the parasite would change its nature, a new variant of Malaria would emerge and research into using the chromosome-transfer technique would advance even further.
Split into simpler sentences: These Indians provided Ross with clues in the belief that in the moment Ross made his discovery, the parasite would change its nature. At this point, a new variant of malaria would emerge and the group's research using the chromosome-transfer technique would advance even further.