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Ferns. What the nature of these bodii - may be is no! so obviou rhey arc 

 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 inner oval, white, and opaque, with an apiculate tubercle at us 

 base, and containing corpuscles of two kinds, the one angular and very minute, 

 i he 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 staminiferous 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 fol- 

 lowing passage : " Experiments made upon the germination of Salvinia and 

 Pilularia have long since shown that in these plants the larger globules were true 

 seeds ; and analogy permitted us to entertain the same belief in regard to Mar- 

 silea and Azolla ; but it remained to be proved that the other bodies were really 

 staminiferous organs, the action of which is necessary to fertilize 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 staminiferous 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 expe- 

 riments of Savi, he has not obtained the same results, and that the seeds, when 

 separated from the supposed staminiferous organs, developed perfectly." I am 

 not acquainted with the particulars of these experiments, nor do I know with 

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

 served ; 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 thecse ; 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 analogous to the 

 larger bodies, or thecre of Marsilea, and the other what have been considered 

 staminiferous 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 mysterious. Mr. Brown, who had good opportunities 

 of studying Azolla in New Holland, with Mr. Ferdinand Bauer's acuteness and 

 profound knowledge of structure to assist him, could arrive at no certain conclu- 

 sion. The involute 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 affinity to Ferns ; but the habit of Azolla is rather that of some Hepa- 

 ticse. Marsileaceae may be considered to occupy an intermediate position be- 

 tween these tribes. Authors have not stated whether ducts are to be found in 

 Pilularia, Salvinia, and Azolla ; they are present in abundance in Marsilea, 



