332 Dr. E. Stva.sburgcr on Fertilization in Ferns. 



frequently many-celled. In unicellular antlicridia the whole 

 space becomes the mother cell of the spevmatozoids ; in those 

 consisting of many cells the central cell alone becomes the 

 mother cell. By a series of partitions the mother cell is 

 divided into numerous small cells, which arc the special mother 

 cells of the spennatozoids ; each of these j)Ossesses a distinct 

 nucleus ; by mutual pressure they become at lirst polygonal ; 

 their arrangement then becomes confused, the nucleus disap- 

 pears, giving place - to a uniformly granular mass. A rose- 

 coloured vacuole soon appears in this mass, the protoplasm 

 gradually retreats towards the walls of its cell, tlic central 

 vacuole becoming proportionally enlarged ; small granules 

 next appear suspended in the fluid contents, the protoplasm 

 collected against the cell-walls divides itself into a spiral band, 

 which, commencing from a single point, describes several coils 

 around the central vacuole. During this process the special 

 mother cells assume more and more a globose form, and sepa- 

 rate themselves from each other, their walls gradually be- 

 coming more delicate. The lateral cells meanwhile are com- 

 pressed by the increasing volume of the contents of the central 

 ones, and the upper or crown cell is filled by the special mo- 

 ther cells. If the antheridium be now placed in water, the top 

 cell is ruptured in a stellate manner by the expansive force of 

 the contents, and the special mother cells make tlieir escape 

 through the opening. The annular lateral cells of the com- 

 pound antheridia now become of use ; for, as the special mo- 

 ther cells make their exit, the fonner increase in bulk, and 

 force the remaining special mother cells out of the central cell. 

 The spermatozoid commonly lies quiet for so long a time as the 

 special mother cells require for opening ; its coils are closely 

 pressed one on another within the cell, and must exercise a 

 certain elastic force on its walls. The softened membrane at 

 last gives way, the spiral coil suddenly unfolds itself, and the 

 sj)ermatozoid moves rapidly away. The special mother cell 

 now disap])ears. During its motion the spermatozoid turns 

 rapidly on its axis ; its body forms three or four coils, which 

 become wider as they recede. The foremost naiTow coils are 

 beset with long cilia : on the last and widest coil a colourless 

 vesicle is visible, containing numerous minute granules ; this 

 seems to be the vacuole before noticed in the contents of the 

 special mother cell. The vesicle is adhesive ; and the sperma- 

 tozoid may be sometimes seen hanging on by it to foreign 

 bodies, where it struggles to free itself, in failure of which, 

 the hinder end of the spermatozoid ]>roduces itself into a long 

 tiiread, which is eventually torn asunder. The vesicle swells 

 out in water ; and if the spermatozoid cannot get quit of it, it 



