6 THE FERN BULLETIN 



erations that alternate with each other cannot be too 

 strongly emphasized. The fern-plant as commonly re- 

 cognized, therefore, is but half a fern. It is the other 

 and less familiar half that we purpose considering in 

 this article. 



When an asexual spore from one of the sporangia 

 on the back of a fern frond falls in a place suitable for 

 germination, it begins to grow, forming new cells by 

 the repeated division of the original one. Soon, there 

 is formed a flat, green, scale-like object, usually heart- 

 shaped and approximately a quarter of an inch in di- 

 ameter. This is the prothallium of gametophyte. It 

 is attached to the soil by slender, hair-like structures, 

 called rhizoids by means of which it absorbs the mois- 

 ture that, together with the carbon-dioxide of the air, 

 forms its food materials. The building of the food is 

 carried on by certain small bodies in the cells, called 

 chloroplasts, which derive their energy from sunlight 

 by means of the green coloring matter of plants or 

 chlorophyll. The gametophyte of the grape-ferns 

 (Botrychiutn), the adder'stongues (Ophioglossum) 

 and various club-mosses (Lycopodium) , lack this 

 green color, and cannot alone form their own food. 

 They have therefore gone into partnership with var- 

 ious minute fungi in order to secure a living. 



As the development of the gametophyte proceeds, 

 there begin to appear upon the older parts certain 

 small structures called antheridia. These are borne 

 on the under side of the plant and, at maturity, consist 

 of three or more cells enclosing a number of male 

 gametes called sperms. The sperms are slender, rib- 

 bon-like objects, coiled cork-screw fashion and fur- 

 nished near one end with numerous hair-like cilia. 



If the gametophyte happens to have difficulty in se- 



