Slide showing chart of 'specific sensitivities of head- and tail- organisers to lithium'. Slide shows 'specific sensitivities of head- and tail- organisers to lithium'. The 'X' axis shows 'morphological age' from 9 to 13, the 'Y' axis shows '% defects'. Chart title at top reads 'Lehmann'. Chart has five lines, all with corresponding symbols which are explained below the chart. The explanation reads as follows: 'x - head organiser, anterior O [black circle] head organiser, posterior O [white circle] trunk organiser, anterior, [upside-down triangle] trunk organiser, posterior, [upright triangle] tail organiser'. Title below chart reads: 'Fig. 147 - specific sensitivities of head- and tail- organisers to lithium'. Late 19th to early 20th Century