CRYPTOGAMS 349 



406. 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 reproduc- 

 tion as effectually as the sexual spores of the bryophytes. 

 The fertile frond, or part of a frond, on which they are borne 

 is called a sporophyll (spore-bearing leaf), and the entire 

 plant is the sporophyte, which, with its crop of spores, makes 

 up one generation. 



It is important to observe that in the ferns and in all pteri- 

 dophytes the sporophyte is the conspicuous and highly 

 organized body that is commonly recognized as the normal 

 growing plant; while with the bryophytes just the reverse 

 holds true, the sexual generation, or gametophyte, repre- 

 sents the normal plant structure, while the sporophyte is 

 an insignificant appendage 

 which never attains an 

 independent existence. 

 Broadly speaking, in bryo- 

 phytes, it is a spore fruit ; 

 in the pteridophvtes and 

 spermatophytes a highly 

 developed plant. 



407. The gametophyte. 

 When one of these asex- 



FIGS. 501, 502. Prothallium of a common 



Ual Spores germinates, it fern (Aspidium): 501, under surf ace, showing 

 i , , { ^Irmt rhizoids, rh, antheridia, an, and archegonia, 



produces, not a fern plant ar . 602 ; un ' dcr surface of an oldergameto . 



like the One that bore it, phyte, showing rhizoids, rh, young sporo- 

 i i i phyte, with root, w, and leaf, b. 



but a small, heart-shaped 



body like that shown in Fig. 501. Examine one of these bod- 

 ies carefully with a lens. Observe that there are no veins nor 

 fibrovascular bundles, and the whole body of the plant seems 

 to consist of one uniform tissue. Compare it with the forked 

 apex of a branching thallus of a liverwort. Do you perceive 

 any points of similarity ? The two are, in fact, morphologi- 

 cally the same. This heart-shaped body is called a prothal- 

 lium, and is the gametophyte of the fern. It may be of 



