THE FERN BULLETIN 



9 



brids, of course, have originated in the first way and it 

 is a matter of wonder that a greater number of natural 

 hybrids have not been recorded since the possibilities 

 are in favor of it. In species like Equisetum, in which 

 the gametophytes are dioecious, that is, each produces 

 but one kind of sex-organ, fertilization of the egg by 

 sperms from another garnet ophyte is the natural 

 course. 



In rare cases the gametophyte may omit the forma- 

 tion of a fern-plant by means of a sexual spore and 

 produce a new fern-plant directly from a bud. This 

 is known as apogamy. In some species the gameto- 

 phyte thus give rise to several branches, each of which 

 may produce a new plant or penetrating the soil, form 

 tuber-like growths from which new plants subse- 

 quently spring. 



When the sexual cell or spore begins to grow, it 

 increases in size by the repeated division of the orig- 

 inal cell just as the asexual spore does, but unlike that 

 spore , it does not fall from the plant. From one sec- 

 tion arises the first leaf, from another the stem, from 

 another the first root and from the last an organ 

 called the foot by means of which the young sporo- 

 phyte absorbs food from the gametophyte until it is 

 able to get food for itself. Some of the structures 

 developed by the new sporophyte mark a long step in 

 the evolution of the fern and serve to sharply dis- 

 guish them from plants lower in the scale of life. For 

 instance, the ferns are the first plants to have true 

 roots. The mosses, to which the ferns are near allied 

 produce rhizoids as the fern gametophyte does, but 

 never roots. Again, the moss gametophyte may be 

 leafy while the sporophyte never is ; in the ferns this 

 is exactly turned around for here it is the sporophvte 

 that is leafy and the gametophyte not. 



