AZOLLA AND SALVINIA. 



543 



been observed in pheenogamous pollen exterior to the ovu- 

 lum.* 



It is scarcely, however, to be expected that analogies, pro- 

 ducable through every stage of any particular process in 

 plants very much differing in general organization, should 

 be found ; so I do not lay stress upon the possibility of the 

 elongation, just referred to being reduced to such an al- 

 most inappreciable amount as might perhaps occur in a 

 Gymnospermous ovulum with exserted embryo sacs. 



A difficulty may also be considered to be presented by 

 the existence of the hairs round the base of the ovula. For 

 these in their structure resemble what I suppose to be the 

 male organs of Fern, and also the anthers of certain Mosses 

 and Hepaticae ; although the terminal cell presents less gra- 

 nular matter than usual. 



In the respect of the supposed males, Azolla presents 

 greater analogies with phanerogamous plants, than either 

 Musci or Hepaticae, in which nothing analogous to pollen 

 grains has been, I believe, yet observed in the anther ; which 

 again can scarcely in all cases be considered a grain of pol- 

 len, the view suggested by the contents. Still even with the 

 objections before mentioned the analogies are as tenable I 

 think as those existing between the pistilla of Mosses and 

 of phanerogamous plants ? those organs in the former being 

 originally closed, in the latter, theoretically at least, original- 

 ly open. 



General objections may be raised from the fact of monili- 



* A remarkable circumstance was observed once or twice in some of 

 the joints of the moniliform filaments, while attached to the axis. Some 

 of them were a good deal enlarged, of a yellow green tint, with a nu- 

 cleus towards either end, or with only one near the base when the en- 

 larged joint happened to be the terminal one. Others near the terminal 

 ones had become divided into two by aline cross the middle, the two cells 

 thus resulting being broader and more beadlike than before. In some 

 others again close to either end was a small nucellus, which corresponded 

 with the contiguous nucelli of the neighbouring joints : and near each 

 nucleus was observed the shadowing out of a large cell. 



