On Azolla and Salvinia. 249 



The great development of a particular spore of a particu- 

 lar capsule, and the corresponding abortion of all the rest, is a 

 second peculiarity. This, which has not been observed in 

 Musci, Hepaticse, or Filices, occurs in a marked degree in 

 Marsilea* and Pilularia ;f and there is also a tendency to it, 

 though not confined to different capsules, in Isoetes and 

 Psilotum. And this, to which the dissimilarity of the mature 

 reproductive organs is mainly attributable, thus becomes so 

 general, that it obviously relates to something important, and 

 will probably be found to exist in particular portions of the 

 families just mentioned as exceptions. 



Mr. Valentine,J was so far as I know, the first who dis- 

 tinctly attributed this want of uniformity to abortion, an 



* A second examination of Marsilea has not presented to me any thing corrobora- 

 tive of M. Fabre's statement. So far as the development of the two difform bodies 

 (capsules) themselves is concerned, there is a manifest agreement with Pilularia, 

 Salvinia, and Azolla. The germinating body is equally derived from the excessive 

 development of a single spore of one capsule, and the abortion of the rest. The 

 other capsules contain spores in a state of uniform development, forming the sup- 

 posed pollen of some Botanists. 



Marsilea evidently appears to connect Salvinidae with Filices ; its important dif- 

 ferences from Salvinidee consist in the capsules, which correspond to the secondary 

 capsules of that family, being developed within the substance of a modified leaf, 

 in their occuring mixed with each other, and in the spores of the pedicellate cap- 

 sules not becoming imbedded in apparently cellular masses. I have not observed 

 anything indicating fecundation. 



f Mr. Valentine, (Linn. Trans, loc. cit.) appears to have no doubt of this 

 in Pilularia. M. Endlicher* thinks it may be so in Salvinia, and makes it part 

 of his generic character of Pilularia and Marsilea, (op. cit. p. 68,) at least so far 

 as the term sporangia abortiva may be considered to indicate abortive spores. 



But I think their great comparative number, the at least equal development of 

 their capsules in Salvinia and Azolla, their appearance, and their subsequently con- 

 taining granular matter, objections to this, though none of them can be considered 

 conclusive. Still it is not to be denied, that if compared with the mature spores of 

 Filices, Musci, Hepaticse, in all which the spores have hitherto been found 

 uniform, they exhibit an apparently imperfect state of development. 



t Valent. Linn. Trans, xviii. p. 491, 497, t. 35, f. 34, 35, 36. 



*Gen. PI. p. 67, in annot. in Salvinia. 



