292 



PLANT LIFE. 



fertilized. In tliese jilants, therefore, we return to a con- 

 dition which is scarcely an alternation of sexual and spore- 

 producing phases, because the 

 sexual phase is nearly obliterated 

 li\- reduction. 



395. Relative size of gameto- 

 phyte and sporophyte. — The ac- 

 companying diagram (fig. 335) may 

 roughly illustrate the history of 



Fig. 334. 



Fl(.. 334. — End of niegas]iiirc of f\'ly^on!tiii di-'ar u at a jt: , c . c%%\ s, J, synerei- 

 d^t. probafjly sterile eggs. P.elow c the nucleus from wliose di\'isions arise the cells 

 of the belated gametophyte Magnified 540 diam, — After .Strasburger. 



Fit; 335 — Diagram representing the reduction of gametophyte and increase iit sporo- 

 phyte from lower to higher plants, a, green alga;; /', red alg;E ; t, liverworts ; d, 

 mosses ; f, ferns ; J\ cliib-mosses ; i', gyninosperms ; /; , angiusperms — Original. 



develo|iment of these phases in the vegetable kingdom. 



The gametophyte phase is represented by the dotted area. 

 It has its greatest dc\'clopment in the lower algce and fungi, 

 where it constitutes the whole, ■ diminishes at llrst slowh- and 

 then rapidly. ,\ftci" the feriiHorts are passed it constitutes a 

 relali\el)' inconsiderable part of the plant and almost disap- 

 ]iears among angiospei'ins. ( )f the sporophyte, represented 

 by the white area, the re\erse is true. The lines crossing 

 the diagram at various levels show by their length in the 

 white and black areas the relati\'e importance of the two 

 phases in the groups indicated. 



