13G STRUCTURAL BOTANY 



of the neck ultimately consists of six rows of cells 

 surrounding the canal. The ventral part of the wall, 

 enclosing the ovum, becomes two layers in thickness, 

 and the whole archegonium is seated on a multicellular 

 pedicel. Apart from this last point, the final form of 

 the archegonium is similar to that in the Liverworts, 

 the chief difference consisting in the marked apical 

 growth which goes on in the archegonium, as in other 

 organs, of the true Mosses. When ready for fertilisation 

 the terminal cells of the neck separate widely from each 

 other, leaving an open passage into the canal, which now 

 only contains the mucilage derived from the disorganised 

 canal-cells. 



Fei tilisation, as in Cryptogams generally, takes place 

 under water. Eaindrops, which have fallen on open 

 male " flowers," and become impregnated with the dis- 

 charged spermatozoids, trickle down on to the lower 

 female plants, and some of the water, carrying the 

 spermatozoids with it, may make its way between the 

 leaves of the archegonial bud, and reach the archegonia 

 themselves. In this way the active male cells are 

 brought into the neighbourhood of the female organs. 

 The rest of the journey they must accomplish by their 

 own movements. Experiments precisely similar to those 

 described in the case of the Ferns have been successfully 

 carried out on Mosses, and here also it appears that the 

 archegonia attract the visits of the swarming sperm-cells 

 by means of a chemical secretion. In Mosses, however, 

 it is not malic acid, but sugar (cane-sugar), which forms 

 the bait. The spermatozoids having been thus lured to 

 the archegonium, penetrate the neck-canal, and one 

 of them ultimately reaches the ovum and effects fertilisa- 

 tion. 



