276 Prof. P. M. Duncan on the Nervous System of Actinia. 



muscular layer, and which communicates with a ramifying tissue in con- 

 tact with the other muscular layers, and that this ends in long fibres 

 which supply the wide fibres of this last-mentioned layer. 



The diffused nature of this nervous tissue is what might be anticipated 

 would be found in animals possessing such general irritability of tissue, 

 and probably its function is to assist in the reflex movements of the 

 animal, and to produce expansion of the disk on the stimulus of light. 



DESCRIPTION OF THE PLATES. 

 PLATE II. 



Fig. 1, which is an outline of a chromatophore, with two small ones close to it, is 

 magnified 10 diameters ; all the rest are drawn from nature under the mag- 

 nifying-power of a -J^-inch immersion lens and a medium eyepiece. 



Fig. 2. Bacilli. 



Fig. 3. Granular and cellular protoplasm between bacilli. 



Fig. 4. Large refractile cells. Haimean bodies. 



Fig. 5. Type a of a Eottekfp body. 



Fig. 6. j3 



Fig. 7. ,, y ,, ., with a thread. 



Fig. 8. Granular and cellular tissue between the Haimean bodies. 



Fig. 9. Same kind of tissue in contact with a Eotteken body. 



Fig. 10. Some cells with refractile nuclei in the tissue. 



Fig. 11. Portion of tissue from amongst the Eotteken bodies. 



Fig. 14. The same, with a forked end. 



Fig. 12. Three portions of intermediate tissue ending in the layer of granular cells 

 which underlies the Eotteken bodies. 



Fig. 13. Haimean and Eotteken bodies and the intermediate tissue in position. 



Fig. 15. A diagram, but very close to nature, of the relative position of the histological 

 elements of the chromatophores. 



Fig. 16. Haimean and Eotteken bodies intermingled. 



Fig. 17. Haimean bodies surrounded by pigment-cells, and with bacilli flat upon them, 

 owing to pressure. 



Figs. 18 & 19. Fusiform nerve-cells. 



Fig. 20. A nerve-cell. 



Fig. 21. Nerve-cells connected and with fibres. 



Fig. 22. A spherical nerve-cell with processes joining the plexus. 



Fig. 23. Eaniifications of the plexiform cord. 



Fig. 24. Nerve-cell and fibres. 



PLATE III. 



Fig. 25. Nerve in relation to the small muscular fibrils of the base. 

 Fig. 26. Nerve ramifying and supplying wide muscular fibre. 

 Fig. 27. A loop of nervous fibre. 



Fig. 28. Terminal ends of the plexus passing over muscular fibre. 

 Figs. 29 & 30. The same, more highly magnified. 

 Fig. 31. The plexus under the endotbelium. 



