332 Dr. E. Strasburger on Fertilization in Ferns. 



fVcquentlj many-celled. In unicellular antlieridia the whole 

 space becomes the mother cell of the spermatozoids ; 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 are the special mother 

 cells of the spermatozoids ; each of these possesses 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 Avails of its cell, the central 

 vacuole becoming proporti(mally enlarged ; small granules 

 next appear suspended in the iiuid 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- 

 tlier 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 their 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 former 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 

 s])ermatozoid moves rapidly away. The special mother cell 

 now disappears. 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 narrow 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 

 Iwdies, where it struggles to free itself, in failure of Avhich, 

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

 thread, which is eventually torn asunder. The vesicle swells 

 out in water ; and if the s})ermatozoid cannot get quit of it, it 



