KEPKODUCTION 



445 



other prothallia than their own is not at all difficult. After 

 their liberation they are attracted to the archegonia by 

 some constituent of the mucilaginous matter which is 

 excreted from their necks when they open (fig. 181). In 

 the Mosses this has been ascertained to be cane-sugar, in 



FIG. 180. ANTHEROZOIDS OP Moss (A) AND FERN (B). 



the Ferns it is malic acid or one of its salts. In the Bhodo- 

 phycese and such Ascomycetes as exhibit sexual reproduc- 

 tion, the passive male gamete, often called a spermatium 

 instead of an antherozoid, is floated to the female organ or 

 its trichogyne by currents in the water. 



FIG. 181. DEVELOPMENT OF THE ANTHERIDIUM IN THE FERN. (After Kny.) 



1, 2, 4, 5, 7, 8, 9, Successive stages. 3, 6 transverse sections of the 

 neck region of 4 and 5. 



In the Spermophytes, where the female gametophyte is 

 always attached to the parent sporophyte, such a" means 

 of fertilisation is of course impossible. For fertilisation to 

 take place it is necessary that the two gametophytes shall 

 be produced in close propinquity to each other. This is 

 effected by the bringing together of the two spores con- 

 cerned in developing them. The microspore or pollen-grain 

 is carried by various means to the neighbourhood of the 



