RHIZOCARPE^ 



27 



lical point becomes cut off by a septum, forming the neck-canal-cell. 

 ow this a second very small portion of the central cell is again cut off 

 form the ventral canal-cell, so that the canal now consists of two 

 s. These two cells become transformed into mucilage, which escapes 

 forcing apart the four apical or stigmatic cells, leaving an open canal 

 the meantime the protoplasm of the large basal portion of the central 

 has become transformed by contraction into the oosphere. The 

 legone is now ready for impregnation, the antherozoids reaching the 

 phere through a funnel-shaped depression in the epispore and the 

 n canal. After fertilisation the canal again closes up by the expan- 

 1 of the stigmatic cells. The 

 begone of Azolla resembles that 

 aalvinia in all essential points. 

 The male prothallium of Salvinia 

 educed to a mere rudiment. The 

 xospores lie imbedded in a mass 

 ardened, granular, frothy mucilage, 

 ned by the disorganisation of the 

 stal cells. They do not escape 

 n this mucilage, but the endospore 

 sach develops into a tubular fila- 

 it which pierces through the muci- 

 ; and the wall of the sporange. 

 ; extremity of this filament which 

 jects outside the sporange is 

 /ed, and becomes cut off by a 

 tum. The lower and larger of the 

 cells thus formed is regarded as 

 dimentary prothallium ; the termi- 

 cell, which again divides into two, 



a rudimentary antherid. The protoplasm of each of the two 

 leridial cells divides into four, and each of these eight masses of 

 :oplasm escapes as an antherozoid. Each antherozoid is a corkscrew- 

 coil of protoplasm, bearing vibratile cilia of great length at its 

 ider extremity. To the same extremity is attached a vesicle, corn- 

 ed of a portion of the protoplasm of the ahtheridial cells which 

 not used up in the formation of the antherozoids, and which does 

 leave the antherozoid during the period of its ' swarming.' 

 The developrhent of the multicellular embryo from the fertilised 

 )erm has been very carefully followed out in Salvinia. The first 

 nentation is by a nearly vertical wall (at right angles to the surface 

 le- prothallium) into two somewhat unequal portions, each of which 



Fig. II. — Sahnnta natans. A, micro- 

 sporange, with microspore-tubes si, 

 ( X looO £, microspore-tube ( x 200) 

 with closed, C with empty antherid. 

 2?,_ antherozoids ( x 600). (After 

 Pringsheim.) 



