253 



aggi-egation of these granules in the centre of the cell, is partially sup- 

 plied in a passage from Mohl, given as a foot-note at p. 567, from 

 which we make the following extract. 



" The young capsules (of Equisetum variegatum) are filled \vith a very delicate, 

 polyhedral, cellular tissue. These cells are connected together in greater or lesser 

 masses, without, however, being surrounded by mother-cells (if they are not rather 

 themselves to be so regarded), and are filled with a granular mass. In older capsules 

 these cells are larger and distinct from each other, and the green granular contents 

 fonn for the most part a disc lying in the middle of the cell. In still more advanced 

 capsules this green disc is changed into an oval grain, wrapped round with the two 

 elaters. * * — Flora, 1833, pp. 45, 46." 



The spores are at first oval or ovate in shape, but they soon be- 

 come globular, which form they afterwards retain : on the contrary 

 the cells, which previously had an angular form from mutual pressure, 

 " gradually acquire substance, separate from each other, and, chan- 

 ging their form, become first globular, and afterwards oval integuments 

 of the spores; the spaces caused by their separation being filled 

 up with a dark green viscid fluid containing abundance of minute 

 granules." 



*' The next change which the integument undergoes is in the development of the 

 spiral sutures, by which it is divided into two narrow bands with broad and rounded 

 ends: at first the dividing lines are indistinctly seen traversing the iutegiiment; after 

 a time they become more distinct, and their spiral direction becomes evident. Two 

 lines of separation run in a spiral direction round the integument, and meet in a sinu- 

 ous transverse suture at each end : these lines cut the integument into two equal parts, 

 the ends of which are dilated and uniform ; and these are the clavate ends of the fila- 

 ments which have been considered by Hedwig and others as forming part of a sexual 

 apparatus. The separation of the integument into parts takes place immediately after 

 the edges of the sutures have arrived at their proper thickness ; it is therefore very dif- 

 ficult after this to find the integument entire. 



" The spore at this time contains a greenish-coloured fluid mixed with some mi- 

 nute granules ; soon after it changes to a deeper green colour, its contents become 

 thicker, less soluble in water, and filled with a greater number of granules ; the fluid 

 which had previously filled the integument and the rest of the thcca is gradually ab- 

 sorbed, leaving the granules which it contained sticking in masses to the spores and to 

 the separated portions of the integument. It is these masses of granules, when found 

 adhering to the filaments in the ripened state of the spore, that have been mistaken 

 for pollen-grains : when removed by means of water, they are found to consist exclu- 

 sively of the lesser granules, the larger ones having now altogether disappeared. As 

 the spore swells, the divisions of the integument are forced asunder ; a portion at each 

 end however generally adheres longer ; and although further separated, these divisions 

 are still held in their spiral position until the ripening of the spore, when, being eject- 

 ed from the theca, they recoil with a jerk, and immediately twist into narrow clavate 

 filaments, the state in which they have been most frequently observed.'' — p. 569. 



