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position, to the sori of Ferns, What the nature of these bodies may be, is 

 not so obvious. ' They are represented as being of two kinds ; the first, called 

 the capsule (?), being an oval stalked case, having two integuments, of which 

 the outer is reticulated and hyaline, the inntjr oval, white, and opaque, with 

 an apiculate tubercle at its base, and containing corpuscles of two kinds, 

 the one angular and very minute, the other much larger and roundish ; the 

 second, much smaller bodies, called the anthers (?), being little sacs filled 

 with yellowish roundish granules, and attached by fours to the stalk of the 

 capsule. 



The structure of Pilularia is of an analogous kind. The exact nature 

 of the parts called anthers is unknown ; from the name that has been 

 given them, it has been supposed that they were similar to the male 

 apparatus of flowering plants ; but this view is altogether gratuitous, and 

 has not been taken from any direct evidence. It seems more probable that 

 they are abortive sacs, analogous to the larger bodies. With regard to the 

 latter, M. A. Brongniart has the following passage: — " Experiments made 

 upon the germination of Salvinia and Pilularia have long since shewn that 

 in these plants the larger globules were true seeds ; and analogy permitted 

 us to entertain the same belief in regard to Marsilea and Azolla ; but it re- 

 mained to be proved that the other bodies were really male organs, the 

 action of which is necessary to fertilise the seeds. This, Professor Savi, of 

 Pisa, had appeared to have demonstrated. Salvinia grows abundantly near 

 that city, and there was no difficulty in procuring fresh plants for the purpose 

 of experiment. He put into different vessels, 1st, the seeds alone; 2d, the 

 male globules alone; and, 3d, both mixed. In the first two vessels nothing 

 appeared; in the 3d, the seeds rose to the surface of the water and fully 

 developed. But M. G. L. Duverney has since published a dissertation upon 

 this plant, in which he states that, having repeated the experiments of Savi, 

 he has not obtained the same results, and that the seeds, when separated 

 from the supposed male organs, developed perfectly." I am not ac- 

 quainted with the particulars of these experiments, nor do I know with 

 what degree of care the exact mode of germination in Salvinia has been 

 observed; but it appears more consonant to the analogical structure of other 

 plants, particularly of Ferns and Azolla, to consider the larger bodies, called 

 seeds by these observers, as thecae ; in which I am the more confirmed, by 

 finding it to be the view taken of their nature by Mr. Brown, and Drs. 

 Hooker and Greville. 



In Salvinia and Azolla the vegetation is that of Mosses, or of Junger- 

 mannia, and the organs of reproduction are quite different. The latter 

 consist of two sorts of membranous bags, of which one contains bodies ana- 

 logous to the larger bodies, or thecfc of Marsilea, and the other what have 

 been considered male organs. These, in Salvinia, have been described by 

 Brongniart as spherical grains, attached by long stalks to a central column, 

 and much smaller than what he calls the seeds : their surface is reticulated 

 in a similar manner, and they only burst by the action of water. In Azolla, 

 M. Bauer represents, and Mr. Brown describes, them as from 6 to 9 in 

 number, angular and inserted upon a central body, occupying the upper 

 half of the involucrum, the lower being filled with a turbid fluid. If the 

 real nature of these parts in Pilularia and Marsilea is involved in obscurity, 

 that of the reproductive organs of Salvinia and Azolla is still more myste- 

 rious. Mr. Brown, who had good opportunities of studying Azolla in New 

 Holland, with Mr. Ferdinand Bauer's acuteness and profound knowledge of 

 stnicture to assist him, could arrive at no certain coticlusion. The invo- 

 lute vernation of the leaves of some of these plants and their involucrum 

 being formed out of the involute frond, as in Ophioglossum, indicate a close 



