RUDIMENTARY ORGANS IN PLANTS 147 



separated genera as Blasia, Radula, and Preissia, 

 four cells of equal size are formed, arranged round a 

 centre. One only of these cells proceeds to develop 

 into a plant, and the others simply atrophy. In 

 all probability the Hepaticse have sprung from 

 some ancestor, in which each spore gave rise to 

 four individuals. 



4. Pteridophyta. According to Farlow, 1 in- 

 stances of apogamy the loss of sex such as have 

 just been described as existing among mushrooms, 

 are also exhibited in certain ferns. In some 

 species, 2 the eggs are not fertilized, but the organs 

 of reproduction still persist in a reduced condition ; 

 in other species there are no spores, and the 

 prothalli spring directly from the leaves (apospory). 



5. Phanerogams. Some of the Phanerogams 

 Silene (fig. 58), Melandryum, (fig. 59), Aspara- 

 gus, etc. exhibit unisexual flowers, but have 

 obviously sprung from species of which the 

 flowers were hermaphrodite. 



In Silene maritima (fig. 58) there are herma- 

 phrodite flowers (fig. 58, B), and also unisexual 

 flowers. The female flowers (fig. 58, A) still possess 

 some tiny stamens, each of which is provided with 

 filaments and anthers in a state of degeneration. 

 The male flowers have non - functional pistils, 



1 W. Farlow, Ueber ungesclilechtliclie Erzcugung von Keimpflanz- 

 clien an Farnprothallien. Bot. Zeit., 1874, p. 180. 



2 A. de Bary, Ueber apogame Fame u.s.w. Bot. Zeit., 1878, 

 p. 449. 



