| Description | Slide shows four diagrammatic drawings of the 'results of experiments testing the inductive capacities of head-organiser (invaginated early: the anterior region of the primitive gut-roof) and of trunk-organiser (invaginated late: the posterior region of the gut-roof), and the reacting capacities of the host-tissues at head level and trunk level'.
Diagrams are labelled as follows: 'Head-organiser in head level', 'Head organiser in trunk level', 'Trunk organiser in head level' and 'Trunk organiser in trunk level'.
The first two diagrams have additional labels which are explained in the following key:
'Fig. 67 - diagram showing the results of experiments testing the inductive capacities of head-organiser (invaginated early: the anterior region of the primitive gut-roof) and of trunk-organiser (invaginated late: the posterior region of the gut-roof), and the reacting capacities of the host-tissues at head level and trunk level (see also Fig 68). Head-organiser at head level forms only the head of a secondary embryo with eyes and ear-vesicles; head-organiser at trunk level may form a complete secondary embryo, and the cephalic structures may arise at a level considerably behind those of the primary embryo; trunk-organiser at trunk level produces the trunk of a secondary embryo; ear-vesicles are formed if the secondary embryo reaches to the level of those of the primary embryo. Head-organiser can thus form a head in both head and trunk levels, but trunk-organiser can only form a head in head level; the reaction to trunk-organiser of the host-tissues at head level is to form a head, and at trunk level to form a trunk. Pr.o.v. eye; Pr.a.v. ear, or primary embryo; sec.o.v. eye; sec.a.v. ear (left L, or right R); sec.cycl.o.v. cyclopic eye, of secondary embryo. (Original based on Spemann).'
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