On Azolla and Salvinia. 231 



than the half, consisting of nine lobes (PL 16. /. 15. 16.) 

 (the three uppermost of which are the largest,) mutually 

 united by a remarkable tissue, which on pulling them from 

 their places separates with them in the form of fibrous 

 radicellar prolongations (PL 16. f. 20.) This part (the 

 upper loculus of Brown) is up to a certain period perfectly 

 homogeneous, and even when the nine lobes are evidently 

 cellular, the axis or common attaching portion is grumous 

 and homogeneous. It is by this tissue that the whole 

 mass hangs from the apex of the capsule which separates 

 with it in the shape of a conical calyptra, (PL 16. f. 13. 14.) 

 presenting in the centre a brown mammilla (the original 

 foramen.) The above mass is in apposition below with 

 the upper surface of the yellow sac ; the part of this (i. e. 

 the vertex) so in apposition not being covered by the 

 incrustation (PL 16. /. 17. 18.) The yellow sac is filled 

 with oleaginous particles ; it presents on the centre of its 

 upper face a trilinear mark (PL 16. f. 17. 18.); it is separ- 

 able from the incrustation, which presents an areolate cel- 

 lular-looking surface (PL 16. f. 13. 15. 16. etc.) ; its mem- 

 brane is thick, of a waxy texture, and without markings or 

 any other indications of composition. (PL 16./. 22.) 



The changes in the other organ, appear only to affect the 

 protuberances round the base of the nucleus, which body 

 may be detected unchanged, as I have ascertained by 

 measurements, in the mature organ. All the protuberances 

 undergo the same changes, those next the base of the nucle- 

 us, (or those first developed, or the uppermost,) being the 

 most precocious. A nearly mature capsule will present a 

 complete series of the developments. 



First they appear as small sessile protuberances with 

 slight indications of cellularity and a central cavity (PL 17. f. 

 5.) In the second stage one or two cells will be found 

 to have been developed under the original protuberance, 



2 H 



