120 



Plants Without Flowers. 



Ferns. 



Altho ferns are very common and very attractive plants, 

 both as wild and as conservatory and house plants, yet their life 

 history is not generally known. The whole of even the brie 

 account which immediately follows could hardly be worked out 

 in the nature study class, but it is given for the teacher who may 

 not have been a student in botany. Having traced it once, the 

 judgment of the teacher may be relied upon to select the main 

 features which can be used in this class. 



There are two stages in the life of the plant, during one of 

 which it lives as a very small inconspicuous plant whose very 

 existence is not known to great numbers of admirers of ferns. 

 The fern plant as we see it growing bears spores. A spore when 

 deposited in the proper conditions sprouts and grows into a mi- 

 nute plant which looks as little like a fern as possible. This little 

 plant lives an independent existence and is known as a prothallium. 

 In the course of its life, it produces on its under surface organs 

 which correspond to stamens and pistils of flowering plants (male 

 and female organs). As in the higher plants pollen grains fertil- 

 ize the ovules, so here cells from the male organs called anthe- 

 ridia fertilize a cell in the organ corresponding to the pistil called 

 an archegonium. Then -as a seed is formed in an ovary of a pistil, 

 so here the fertilized cell forms by growth a germ of a minute fern 

 which soon grows up from the prothallium. This tiny fern con- 

 tinues its growth, the prothallium in the meantime dying, until 

 it attains the characteristic size and form of the species to which it 

 belongs. Thus a spore from a fern plant produces a prothallium, 

 and then the prothallium produces a fern like the one from which 

 the spore comes. These two forms or stages, or generations, as 

 they are called, alternating thus, are spoken of in biology as an 

 alternation of generations. 



