258 On Azolla and Salvinia. 



each branch, plumose throughout their whole length, tipped by a 

 calyptra, and surrounded at the base by a short sheath, which may be 

 mistaken for one of the circumcised capsules. 



Leaves opposite, so close together as to become imbricated, espe- 

 cially the lower membranous ones, entire, obliquely ascending, thick, 

 fleshy, outer surface covered with stout whitish papillae of a single 

 somewhat conical cell, the oldest ones rather the smallest, upper ones 

 more or less trapeziform. Under ones quite membranous, hya- 

 line, larger, nearly reniform, with a tendency, especially in the 

 young ones, to have the points incurved ; these are composed of a 

 single layer *oi cellular tissue. 



The growing points especially, present a number of minute con- 

 fervoid filaments, the assumed male organs, which at certain periods 

 may be seen passing into the foramen, the ovula becoming resolved 

 into their component cells within the cavity of that body. 



Organs of reproduction in pairs, attached to the stem and branches, 

 one above the other, concealed in a membranous involucrum. Ovula 

 atropous, oblong-ovate, with a conspicuous foramen and nucleus, 

 around the base of which are cellular protuberances. 



Capsules of each pair either difform — in which case the lowest one 

 is oblong- ovate, the upper globose— or both of either kind, generally 

 perhaps the globose, presenting at the apex the brown remains of the 

 foramen,* and still enclosed in the involucrum. Upper half generally 

 tinged with red. 



The oblong-ovate capsule opens by circumcision ; with the apex sepa- 

 rate the contents, which consist of a large yellow sac contained in a 

 fine membrane, the remains of the nucleus (or the secondary capsule.) 

 The sac is filled with oleaginous granular fluid, and surmounted by 

 a mass of fibrous-tissue, by which it adheres slightly to the calyptra ; 

 on the surface of the fibrous tissue are 9 cellular lobes (the three 

 upper the largest), which when pulled away, separate with some of 

 the fibrous tissue, and so appear provided with radicles. 



* See also Martius, t. 74, f. 10, and Meyen f. 23, for the apex of the round 

 capsule containing the pedicelled secondaries. 



M. Meyen indeed says, his figure is a representation of the base of this organ, 

 his common indusium ; but this is probably a mistake. For the mere punctum 

 in the centre is too small an indication of a rather large hilum, and the disposi- 

 tion of the cells and whole appearance is that of the apex. 



