REPRODUCTION 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 
B 
@ 
Fie. 180.—ANTHEROZOIDS oF Moss (A) AnD FeErwn (B). 
A 
the Ferns it is malic acid or one of its salts. In the Rhodo- 
phycee 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. 
Ree meron. 
Fig. 181.—DrEvELOPMENT 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 
