On Azolla and Salvinia. 229 



jointed, more or less capitate filaments, the head represen- 

 ting the protuberance as it existed originally. (PL 15. f. 10. 



12. 15. 16.) 



The sixth stage presents both organs of a decided pink 

 tint, except the base or often the lower half, the cells of 

 which do not contain a coloured fluid. The apex of both 

 appears distinctly browned, and generally exhibits short 

 moniliform filaments adhering to it. The space between 

 the nucleus and the foramen, is occupied by the joints of the 

 moniliform filaments. Thus far both organs present common 

 appearances. 



But at this stage remarkable dissimilarities begin to be 

 exhibited, and what is equally remarkable these affect either 

 both organs indifferently, or one only of each pair, in which 

 case alone there can be said to be any thing definite in 

 the position of the two. In this case in one organ the 

 developments take place within the nucleus, in the other 

 in the small cellular protuberances round its base. The 

 former becomes the male of Botanists, the latter the female ; 

 or the former becomes the ovate organ presenting the so-cal- 

 led calyptra containing the large yellow sac, surmounted by 

 the curious lobed body; the latter becomes the globular organ 

 containing the numerous, smaller, pedicellate bodies. Of the 

 first, the first change ascertained was the appearance of a 

 grumous condensation in the original nucleus (PL 15. f. 12. 



13. 14.); of the latter, the development of grumous matter 

 in each of the small protuberances round the base of the 

 nucleus, which are developed in a centrifugal order. 



In the first which I now propose to follow, this condensa- 

 tion, for so it apparently is, increases until a tolerably well 

 defined opaque grumous disc is seen in the nucleus : this disc 

 subsequently appears under a certain focus transparent in the 

 centre, opaque round the edges (PL 15. f. 15. PL 16./. 3.); 

 an appearance due, I believe, to the development of a mem- 

 branous sac inside. In the meantime, the pink colour of the 



