Slide showing three microscopic diagrams of 'Inductions of secondary neural tubes produced by implantations of synthetic chemical substances into the blastocoele cavity.' Slide shows three black and white microscopic diagrams of '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. 93, 'Inductions of secondary neural tubes produced by implantations of synthetic chemical substances into the blastocoele cavity. A. 1 : 2 : 5 : 6- dibenzanthraceme-endo-z-B-succinate. B, Anthracene (unpurified). C. Naphthalene (unpurifed). Conventions as in Fig. 91.' Late 19th to early 20th century