530 



MARSILEACE^E, 



At a later period each head (or s. capsule) presents the 

 appearance of being subdivided into several cellular-looking 

 compartments, each of which encloses several of the yel- 

 low sacs (PI. CXXVII. Fig. I.J.) The yellow sacs, wheu 

 separated, present no particular change, appearing generally 

 quite empty (PI. CXXVII. Fig. I.,8.) 



Still later each s. capsule presents generally three or some- 

 times two subdivisions of increased size (PI. CXXVII. Fig. 

 I. ,9, 10.) And this is nearly the mature form, for the further 

 changes only regard the appearance of cellularity in the sub- 

 divisions, and the imbedding of the yellow sacs in the appa- 

 rently 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 (CXIX. Fig. VII., b.). Each contains two or three, 

 sometimes 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 

 prolongations having appearances of cellularity, but not of 

 organic cellularity (PI. CXIX. Fig. VII., c. a.) 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 any thing in common. 



The young state of the Salvinia is too much like that of 

 Azolla to need any detailed remark. But the nucleus presents 

 from an extremely early period a papillar appearance, the first 

 developments of the future secondary capsules taking place at 

 an exceedingly early period. (PI. CXXV. Fig. I., 6, 7- 

 Fig. II., 2., PI. CXXIV. Fig II.,a.) 



The first discrepancy remarked in the organs of this plant 

 consists in the number of the papilla; (future secondary cap- 



