CBYPTOGAMS 201 



weed — and like the zoospores of many Algte — in hav- 

 ing two ciha for locomotion. 



467. The aruhegonial branches bear on the under side 

 at the liase of the rays row.s of flask-shaped organs called 

 areliegonia (Fig. 3-34, u). In the arcliegoniuiu an e<jy cell 

 (e) is situated at the center of the enlarged basal pari. 

 When ready for fertilization the egg may be readied 

 through the canal in the slender portion, or neck, of the 

 archegonium. When the dew is on the plants tlie anthero- 

 zoids make their way to the archegonial branches (which 

 at the season of fertilization are not much grown), and 

 swarm to the mouth of the archegonia. C)]ie of them 

 passes through the canal and fuses with the egg cell. 



468. In most cases of oosporic reproduction in Algre 

 and Fungi, it will be remembered, the oospore falls from 

 the parent plant before it germinates. In Nemalion, 

 however, fertilization of the egg gives rise to a structure 

 organically united to the original plant ; this structure 

 ultimately bears spores (carpospores), serving to dis- 

 seminate the species. Marchantia is like Nemalion in 

 the noteworthy fact that the oiispore gennhtdtes hi posi- 

 tion, and gives rise to spores vnhj after an internal of 

 growth upon^ the pare)it pilant. Kor after fertilization the 

 oospore divides into two, then into four, then into eiglit 

 parts, and so on. The mass of cells llnis originating 

 grows and iinally forms a stalked spore capsule (I'ig. 

 334, c, d), or sp)orogoniu'in. The foot of the sporogonium 

 is embedded in the tissue at the base of the old arche- 

 gonium (ar). 



469. The spores are numerous, free, rounded or some- 

 what angular, walled cells. When the capsule bursts, one 

 sees that it contains a great number of line threads mixed 

 with tiie spores. They have the property of twisting and 

 untwisting with changes of atinospheric moisture, and so 

 serve to give the spores to the winds from time to time. 

 From the spores new plants develop. 



470. The archegonium is a structure that is found in 

 no plant lower than tlie Liverworts. As we go upward, 



