44 . PHARMACEUTICAL BOTANY 



During wet weather the mature antheridial wall bursts open and 

 the many ciliated spermatozoids escape into the water. These' mov- 

 ing in the water are drawn by the chemotactic malic acid to the 

 mouths of the archegonia of another prothallus, and, passing down 

 the canal of each of these, gather around the ovum. One, probably 

 the best adapted, fuses with the ovum and fertilizes it forming an 

 oospore or fertilized egg. 



Origin of New Sporophyte or Diploid Plant from Fertilized Egg. 

 The fertilized egg now rapidly divides and redivides to form octant 

 cells. The octant cells further divide to produce anteriorly a stem 

 rudiment (one cell), first leaf (two cells), second leaf (one cell) and, 

 posteriorly, root rudiment (one cell), foot rudiment (two cells) and 

 hair rudiments (one cell) . 



Growth of Seedling into Mature Sporophyte. The foot rudiment 

 develops into the foot which obtains nourishment from the prothal- 

 lium, upon which the young sporophyte is for a time parasitic. The 

 root rudiment becomes the first root which grows downward into 

 the -soil. The stem and leaves turn upward. In a few weeks the 

 prothallus decays and the sporophyte is established as an independ- 

 ent plant. More roots and leaves (fronds) are developed and ere 

 long continued growth results in the formation of a mature sporo- 

 phyte which presents for examination: (i) a subterranean stem bear- 

 ing several roots; and (2) arid fronds, each of which consists of a 

 stipe or petwle and a lamina or blade, the latter divisible into pinna 

 or lobes and pinnules, upon which last sori are developed. 



Alternation of Generations. It will be observed that in the life 

 cycle of the Male Fern there occur two distinct generations, one, a 

 sporophyte or asexual generation which begins with the oospore and 

 ends with the dispersion of asexual spores; a second, the gametophyte 

 or sexual generation, beginning with the protonemal outgrowth of 

 the spore and ending with the fertilization of the egg to form an 

 oospore. The sporophyte gives rise to the gametophyte which in 

 turn gives origin to the sporophyte. 





