In chapter 10, what happens in the park that terrifiess Dr. Jeky

Jekyll suffered another spontaneous transformation, this time in a park outside of his home. Afraid he would be captured by the police, and unable to return to his home because the servants would see him and report him, Hyde sent for Lanyon's assistance. From that night forward, Jekyll had to take double doses of the potion every six hours to avoid unintentionally waking up as Hyde.