THE VASCULAR CRYPTOGAMS 29 



locomotion of the male cell itself; the spermatozoid 

 moves by means of its cilia, and this can only take place 

 under water. In most Phanerogams the generative cell 

 is carried from the pollen-grain to the ovum by the 

 growth of the pollen-tube; the final result, the union 

 of the nuclei of the two cells, and, no doubt, of certain 



C-- 



FIG. 16. Selaginella ; advanced embryo in longitudinal section. 

 S, suspensor ; R, root ; F, foot ; 0, cotyledons (cell-walls 

 omitted) ; L, ligules ; St. apex of stem ; If, hypocotyl. 

 Magnified 165 diameters. (After Pfeffer.) 



portions of their protoplasm also, is the same in both Sub- 

 kingdoms. It is now ascertained that spermatozoids are 

 formed in certain Gymnosperms. (See p. 303.) 



After fertilisation the ovum surrounds itself with a 

 cell-wall of its own, and soon divides by a transverse 

 septum into two cells. The upper cell, i.e. that lying 

 next to the neck of the archegonium, becomes the sus- 

 pensor, which may undergo a few further cell-divisions 

 (see Figs. 15 and 16, S). The lower cell develops into 

 the embryo itself. Owing to the growth of the suspensor 

 in length, the embryo is carried deep down into the 



