On Azolla and Salvinia, 233 



only regard the appearance of cellularity in the subdivi- 

 sions, and the imbedding of the yellow sacs in the apparently 

 cellular masses hence resulting. 



When quite formed each secondary capsule presents a 

 long simple stalk, a spherical head, formed of one layer of 

 sinuous cells, containing green granules adhering to the walls 

 of each cell (PL 17. /. 19.) Each contains two or three, some- 

 times four, cellular bodies, convex on the outer surface or that 

 next the wall of the cavity, irregular on the inner surface, 

 or that of mutual apposition. This surface presents prolonga- 

 tions having appearances of cellularity, but not of organic cel- 

 lularity (PL 17. f. 20. 21.) The mass is solid and apparently 

 cellular ; within it may be seen the once free trifacial yellow 

 sacs. 



It will be hence seen that in Azolla the difFormity of the 

 mature organs is extreme, indeed but for the foramen, and 

 the trilineal mark of the vertex of the yellow sac, the two 

 could scarcely be considered as having anything in common. 



The young state of the organ of the Salvinia is too like 

 that of Azolla to need any detailed remark. But the nucleus 

 presents from an extremely early period a papillar appear- 

 ance, the first developments of the future secondary capsules 

 taking place at an exceedingly early period (PL 18. f. 1. 

 2. 3. 4. 5.) 



The first discrepancy remarked in the organs of this plant 

 consists in the number of the papillae (future secondary cap- 

 sules) developed. This also occurs at a very early period, 

 when the two subsequently difForm organs are recognisable, 

 the one by the smallness and great number of the papillae, the 

 other by their larger size and smaller number. 



The second discrepancy arises from the greater develop- 

 ment of a particular cell in the secondary capsules resulting 

 from the development of the papillae. Otherwise, at least up 

 to the period of the enclosure of the trifacial cells (or spores) 



