Edward Jenner full-blown infection. Later, he injected Phipps with variolous material, the routine method of immunization at that time. No disease followed. The boy was later challenged with variolous material and again showed no sign of infection. Donald Hopkins has written, "Jenner's unique contribution was not that he inoculated a few persons with cowpox, but that he then proved [by subsequent challenges] that they were immune to smallpox. Moreover, he demonstrated that the protective cowpox pus could be effectively inoculated from person to person, not just directly from cattle. Jenner successfully tested his hypothesis on 23 additional subjects. Jenner continued his research
Edward Jenner of the previously misunderstood life of the nested cuckoo, a study that combined observation, experiment, and dissection. He described how the newly hatched cuckoo pushed its host's eggs and fledgling chicks out of the nest (contrary to existing belief that the adult cuckoo did it). Having observed this behaviour, Jenner demonstrated an anatomical adaptation for it—the baby cuckoo has a depression in its back, not present after 12 days of life, that enables it to cup eggs and other chicks. The adult does not remain long enough in the area to perform this task. Jenner's findings were published in "Philosophical