226 ZOOPHYTES. 



The planula becomes motionless in about eight or nine days after 

 quitting the matrix ; and other seventeen or eighteen elapse before evolu- 

 tion of the hydra. Therefore this Sertularia reaches perfection in about 

 twenty-six days after the planula escapes. 



;■ ■ When the whole planulse of a specimen have forsaken their compart- 

 ments, the mass affording them, previously of a green colour, is now con- 

 verted to grey. After the concentrated nascent hydrse disappear from 

 their cells, those in their decay seem to leave the bulbs at the root, as 

 bearing considerable resemblance to the mass of compartments. 



All the preceding details apply to objects which are very minute. 



No corresponding mode of proiDagation among zoophytes has hitherto 

 occurred to me ; and although the subject of repeated observation, it is 

 sufficiently interesting to merit further inquiry. 



Plate XLII. Fig. 1. Sertularia Arcta. — The Crowded Sertularia. 

 2. Another specimen. 

 8. Margin of the same. 

 4. Margin of Fig. 1 . 

 6. Surface of a mass of compartments. 



6. Portion of the same, showing the orifices left by the escape 



of the planulae. 



7. Planulae. 



8. Planulae metamorphosing. 



9. Nascent Sertularise from the Planulae. 



10. Nascent Serlularise advancing. 



11. Nascent Sertularise in further progress. 



12. Nascent Sertularise with the hydrse protruding from the cell. 



13. Nascent Sertularise far advanced. 



14. Nascent Sertularise. 



15. Nascent Sertularise, originating from the planulae, now come 



to maturity. 

 All the preceding figures, except 1, 2. are enlarged. 



