284 



PEACTICAL BOTANY 



toward the antheridia. The enlarged part of the archegonium, 

 where the egg is formed, is embedded in the tissue of the ga- 



metophyte. The neck 

 opens (Fig. 237), 

 sperms enter, and 

 one of them unites 

 with the egg. The 

 resulting oospore is 

 consequently formed 

 within the gameto- 

 phyte tissue. 



263. The fern plant: 

 the young sporophyte. 

 The oospore begins 

 its growth while still 

 Avithin the gameto- 

 phyte. It soon pro- 

 duces a foot, which 

 absorbs nourishment 

 out of the gameto- 

 phyte. It also pro- 

 duces a root, stem, 

 and leaf, and these 

 beginnings of the 

 leafy plant are called 

 the sporophyte em- 

 bryo. In most ferns 

 the embryo root soon 

 dies and the stem 

 becomes a prostrate 

 underground root- 

 stock from which the 

 new roots grow. The 

 leaf arises into the 

 air and the new sporophyte is thus established (Fig. 235, B') 

 as the chlorophyll-working fern of our common observation. 



Fig. 236. Fern antheridium and sperms 



A, an antheridium from which the sperms are escap- 

 ing ; B, one enlarged sperm. All greatly magnified. 

 After Luerssen 



