Notes from Frank Lillie's lecture. Trinkaus concludes his notes from the preivous page on the development of feathers.Lecturer: F.R. Lillie, Lecture "The feather as a developmental system" (Information taken from the 1939 Embryology Course Book)Page 98 of 113 from the first notebook of lecture and laboratory notes that John P. Trinkaus took during his time as a student in the Marine Biological Laboratory Embryology Course in 1939 in Woods Hole, MA