270 



PEACTICAL BOTANY 



Embedded in the antheridial head are the antheridia (Fig. 224), 

 which open and discharge their sperms in very large numbers 

 upon tlie ujDper surface. The archegonia hang downward from 



the underside of the ar- 

 chegonial head (Fig. 225). 

 The sperms swim, or per- 

 haps are carried by contact 

 with bodies of small ani- 

 mals until they come into 

 the vicinity of the arche- 

 gonia. They enter the neck 

 and one fertilizes the egg. 

 The oospore, therefore, is 

 produced in the arehego- 

 nium, which is pendent 

 from the underside of the 

 archegonial head. 



252. Marchantia: asex- 

 ual reproduction. The oo- 

 spore begins to grow in 

 the position in which it is 

 formed, and soon produces 

 an oblong body, one end 

 of which is the foot and 

 the other the capsule. The 

 foot absorbs nourishment 

 from the archegonial head 

 at the old archegonial base. 

 Within the capsule many 

 spores are produced by di- 

 vision of the interior capsule tissues. Also some of these inte- 

 rior cells form elongated spiral threads, which, when the capsule 

 bursts, twist and squirm about as they dry or become moist. 

 This twisting motion throws the spores from the open tip of the 

 capsule. Tliese spiral filaments which assist in the distribution 

 of spores are called elaters, meaning " drivers," or " Imrlers." 



Fig. 225. Part of an archegonial head of 

 Marchantia in diagram so as to show the 

 archegonia (c) hanging down from the 

 underside of the head. The air pores (p), 

 the clilorophyll cells {chl), and the loose 

 tissue (s) which surrounds the archegonia 

 are also shown 



Modified from Bonnier and Sablon 



