It shews the general features of an embryo of stage H, more especially the relations of the body-cavity in the parietal and vertebral portions of the lateral plate, and the early-formed band of muscle (mp´) in the splanchnic layer of the vertebral plate.
Fig. 6. Section from the œsophageal region of Scyllium embryo belonging to stage I. Zeiss C, ocul. 1. Chromic acid specimen.
It shews the formation of the rudiments of the posterior nerve-roots (pr) and of the vertebral rudiments (Vr).
Fig. 7. Section of a Torpedo embryo belonging to stage slightly later than I. Zeiss C, ocul. 1, reduced 1/3. Osmic acid specimen.
It shews (1) the formation of the anterior and posterior nerve-roots. (2) The solid knob from which the segmental duct (sd) originates.
Fig. 8. Section from the dorsal region of a Scyllium embryo belonging to a stage intermediate between I and K. Zeiss C, ocul. 1. Chromic acid specimen.
It illustrates the structure of the primitive ova, segmental tubes, notochord, etc.
Fig. 8a. Section from the caudal region of an embryo of the same age as 8. Zeiss A, ocul. 1.
It shews (1) the solid œsophagus. (2) The narrow passage connecting the pericardial (pc) and body cavities (pp).
Fig. 9. Section of a Pristiurus embryo belonging to stage K. Zeiss A, ocul. 1. Osmic acid specimen.