FERN PLANTS 257 



ring straightens itself out, ruptures the wall of the spo- 

 rangium, and the spores are discharged with considerable 



49 49i 492 



489-492. Spores of pteridophytes, magnified : 489, a fern spore ; 490, 491, two 

 views of a spore of a club moss; 492, spore of a common horsetail (Equisetum 

 arveuse) . 



force. Compare the spores depicted in Figures 489-492, 

 with the pollen grains in Figures 378-381. Do you notice 

 any resemblance ? 



364. Reproduction. The spores are the reproductive 

 bodies of ferns, and correspond in this respect to the seeds 

 of spermatophytes, but their mode of reproduction is very 

 different, or rather seems so, because here the process 

 known as alternation of generations first becomes apparent 

 to the eye, as we proceed from the higher plants to the 

 lower. The same thing occurs among seed plants also, 

 but as it is there partly concealed within the seed, botanists 

 first became acquainted with it through the study of spore- 

 bearing plants, where it is more clearly revealed. What is 

 meant by it will be better understood after the life history 

 of the ferns has been studied. 



365. The Sporophyte. The spores found in such abun- 

 dance on the fertile pinnae are all alike, and each one is 

 capable of germinating and continuing the work of repro- 

 duction without the necessity of any such union as we saw 

 taking place between the pollen and the ovule in the 

 spermatophytes. The plant or part of a plant that bears 

 these reproductive bodies is called a sporopliyte, or spore 

 plant, and with its crop of spores makes up one generation. 



366. The Prothallium. When one of these spores ger- 

 minates, it produces, not a fern plant like the one that 

 bore it, but a small, heart-shaped body like that shown in 



ANDREWS'S EOT. 17 



