Slide showing two microscopic photographs of an embryo with an organiser graft. Slide shows two microscopic photographs of an embryo with an organiser graft. Photographs are labelled 'a' and 'b'. Photograph 'b' has the following labels: 'induced embryo', 'host embryo', and 'graft'. Title below images reads: 'Fig 18 - An organiser graft in the chick. (a) shows the host embyro with the induced head just to the left of it. (b) is a section'. Late 19th to early 20th Century