Slide showing three diagrammatic drawings demonstrating 'inductions of secondary neural tubes produced by implantations of synthetic chemical substances into the blastocoele cavity'. Slide shows three diagrammatic drawings demonstrating 'inductions of secondary neural tubes produced by implantations of synthetic chemical substances into the blastocoele cavity'. Diagrams are labelled 'A', 'B' and 'C'. Title below images reads: 'Fig 92. - Inductions of secondary neural tubes produced by implantations of synthetic chemical substances into the blastocoele cavity. A. 9:10-dihydroxy-9:10-dihydro-9:10-dibutyl-1:2:5:6-dibenzanthracene. B. Styryl blue. C. 3:4-benzpyrene. Conventions as in Fig. 91'. Late 19th to early 20th Century