CHAP. III. MARSILEACEiE. 223 



acquire the figure of irregular polygons ; the other three- 

 or four-valved thecae, of a similar appearance, containing 

 three or four roundish fleshy bodies, each of which is at 

 least fifty times larger than the granules contained in the 

 first kind of theca, and is said by Brotero to burst with 

 elasticity, — an observation which requires verification. The 

 first kind of theca is found in all species of Lycopodiacese ; 

 the second is only found sunultaneously in a few. The con- 

 tents of both are believed to be sporules ; but no satisfactory 

 explanation has yet been oflPered of the cause of their differ- 

 ence in size, and probably also in structure. I would suggest 

 that the powder-like grains are true sporules, and that the 

 large ones are buds or viviparous organs, as has already been 

 stated by Haller and Willdenow. A writer in the " Transac- 

 tions of the Linnean Society" has figured and described the 

 growth of the larger grains of Lycopodium denticulatvmi, 

 and he considers that they exhibit the germination of a dico- 

 tyledonous plant ; but, independently of any mistrust which 

 may attach to the accovmt, it is obvious enough that his own 

 drawings and description represent a mode of germination 

 analogous, not to that of dicotyledons, but rather to that of 

 monocotyledons, but also reducible to the laws which govern 

 the incipient vegetation of a bud. 



The powder-like sporules are inflammable, and have been 

 supposed by Haller, Linneeus, and others to be pollen, while 

 the larger have been considered seeds ; and to a part of the 

 surface of the theca the office of stigma has been attributed. 

 The thecae themselves have been fancied to be male apparatus 

 bv Koelreuter and Gsertner. 



4. Marsileacece. 



This very curious little order consists of plants differing 

 from each other so much, that, although consisting of only 

 four genera, it is necessaxy to subdivide it into two distinct 

 tribes. As I have never had an opportunitj'^ of examining 

 these plants in a fresh state, I beg to cite the observations of 

 Adolphe Brongniart, who appears to have given them an 

 especial attention. 



In Marsileacese, properly so called, says this botanist, 



