272 On Azolla and Salvinia. 



PI. xix. 



( The development of the sac-containing secondary capsules.) 

 P'ig. 1. Capsule. 



2. One of its secondary capsules, the cell in the centre of 



the grume is the young (subsequently yellow) sac ; 

 those between the central grume, and the inner sur- 

 face of the capsule are young trificials, (abortive 

 spores.) 



3. Another secondary of the same capsule rather more 



advanced. 



4. Another, still more advanced. 



5. The central cell, young (subsequently yellow,) sac de- 



tached ; trilineally marked surface. 



6. Portion of the grumous contents of No. 4, shewing 



parent cells developing, and fully formed, and two 

 young spores. 



7. Confervoid filaments attached to the outside of the 



capsule of No. 4 ; about 500 times. 



8. A young secondary still more advanced, but with the 



central cell abortive, appearing in its original state of 

 a grumous condensation or nucleus. 



9. 10. 11. Parent cells squeezed out of the grume of the 



same secondary capsule. 



12. Another secondary capsule still more developed : cen- 



tral cell (subsequently yellow) sac much more de- 

 veloped ; the surrounding grume much diminished. 



13. 14. Part of the more fluid grumous contents of the 



same : 14. represents what appears to be trifacials 

 just separating : this was only observed once. 



15. Central sac of No. 12. 



16. Another secondary capsule rather more advanced, the 



central sac now commences to assume a yellowish 

 tint. 



17. Another more advanced, shews the mammilla in the 



vertex of the central (yellowish) sac, appearing to 

 pass off into a thin grumous lining of the cavity of 

 the sac. 



18. Sac of the same; trilineally marked face. 



19. Another more advanced : perhaps represents the deve- 



lopment of the three lobes subsequently crowning 

 the (yellow) sac. Analogy with Azoolla ? 



