ALCYONIDIUM. 39 



On December 16, three new portions were generating from the old 

 patch, fig. 4, the under surface being more distinctly exposed. At this 

 time the vigour of the specimen seemed to be exhausted. 



All the progress of the embryos and the cells above described, was 

 admirably seen, the diffusion being over a very transparent watch-glass. 



The preceding comments shew here, as elsewhere, the progress of 

 what we characterise the inorganic parts, apparently depends on the evolu- 

 tion and the increment of those deemed organic, and that they advance 

 together. It has been erroneously maintained, therefore, that the cell gene- 

 rates the hydra, for the hydra rather generates the cell, or both are in- 

 volved by the same elementary principle. 



Plate XI. Fig 1. Alcyonidium mytili. 



2. The same enlarged. 



3. Another specimen detached November 2. 



4. The same entire, with three new portions a, b, c, as generating 



on December 16. Under surface enlarged. 



5. Specimen shewing the cellular formation in a portion of the 



upper surface, enlarged. 



6. Portion shewing the angular formation below. Under surface 



enlarged. 



7. Hydrce of fig. 3. 



8. Hydrce of another specimen. 



9. Gemmules? in the substance of fig. 6. 



10. Generating border a of fig. 3, as on November 14. 



11. The same as on November 19. 



12. Embryonic hydra in the new cells of fig. 11. 



13. New border of cells generating from fig. 4 at c, as appearing 



on November 19. 



14. The border, fig. 10, as augmented on December 2. 



All the preceding figures, unless the first and third, are en- 

 larged. 



