570 Mr. Hassall on4he Structure of the Pollen Granule. 



taining flowers for the purposes of my inquiry, without which 

 the extent of my investigations must have been much nar- 

 rowed. My best thanks are hkewise due to Dr. Lindley, to 

 Mr. Loddiges, and Mr. Anderson of the Chelsea Gardens, for 

 a similar favour ; but more particularly are they due to Dr. 

 Lindley. To Mr. Choules of the Kew Botanic Gardens I 

 am also much indebted for the correction and revision of the 

 list of species. 



I have now brought to a termination but one of a series of 

 papers which it is my intention, if health and time permit, to 

 publish on the subject of the pollen granule. 



EXPLANATION OF THE PLATES. 

 All the figures are drawn to the same scale, and exhibit the relative sizes 

 of the pollen granules. 



Plate XIIL 

 Fig. 1. Pollen granule of Cyperus longus. 



2. of Papyrus Antiquorum. 



4. of Zea Mays. 



5. of Typhalatifolia, 



6. ' of Calla palustris. 



7. of Calla aethiopica. 



8. of Juncus lacustris. 



9. of Limnocharis Humboldtii. 



10. ■ of Tradescantia ; side view. 



11, 12. Pollen granule of Asparagus officinalis ; 11, front view, exhibit- 

 ing the single furrow with which it is furnished ; 12, end view. 



13, 14, 15. Pollen granule of Lilium longiflorum ; 13, front views; 

 14, end ditto ; 15, the appendage which rests upon and partly con- 

 ceals the furrow. 



16. Pollen granule of Watsonia irioides. 



17, 18, 19. Represent three views of the pollen granule of Anigozan- 

 thus coccineus; 17, front aspect; 18, side ditto ; and 19. exhibits its 

 form when upon the stigma and just about to emit its two pollen 

 tubes. 



20, 21, 22, 23. Represent the pollen granule of Crinum amabile ; 20, 

 front view; 21, a section of the granule; 22, the form which it as- 

 sumes previous to the emission of the pollen tubes ; 23, one of the 

 appendages to the furrows. 



24, 25, 26 : 24, front view of the pollen granule of Pancratium decli- 

 natum ; 25, side view ; 26. exhibits the intine with its contents just 

 escaping through the fissure in the extine ; 24 a, appendage. 



Plate XIV. 

 Fig. 30, 31. Pollen granule of Strelitzia humilis ; 31. shows the manner in 

 which the extine cracks either on coming in contact with solutions 

 of the mineral acids or when applied to the stigma. 

 32, 33. Pollen granule of Canna occidentalis ; 32, in its dry state ; 



33, as it appears in water or in solutions of the mineral acids. 

 34, 35. Pollen granule of Pinus sylvestris; 34, side view; 35, front do. 



37. Pollen granule of Nerium Oleander as seen upon the stigma. 



38, 39, 40, 41, 42. Different views of the pollen granule of Petunia vio- 

 lacea ; 38, a side view of it in its primary or dry state; 39, end do. ; 

 40, the form which it assumes in water; 41, as it appears upon the 

 stigma ; 42. exhibits the extine detached from the intine. 



