PROTHALLUS 



27 



been thus dormant for a considerable time have been seen to revive 

 when soaked out, and to continue their growth. They share in some 

 measure that faculty which is so important to many Bryophyta, of recovery 

 after dormancy under drought. Comparing the prothallus with the Fern- 

 Plant as regards the water-relation, it is plainly less adapted for life on 

 exposed land-surfaces, and more immediately dependent on moisture. 



. FIG. ii. 



i. An attenuated male prothallus of Ncphrodium Filix-mas ; 2-5. stages of development 

 of antheridia ; 6, 7. juptured antheridia ; 8. a spermatozoid. (After Kny.) 



The prothallus thus constituted is capable in some cases of vegetative 

 propagation, by gemmae, and other forms of " gametophytic budding," 

 but this does not occur in the Male Fern. 



Though the close dependence on moisture for functional activity is 

 thus seen in the prothallus, it is much more obvious in the behaviour 

 of the sexual organs which the prothallus bears. These in the Male Shield 

 Fern a are commonly borne, male and female, on the same individual 



1 It is hardly necessary to say that the "Male" Fern is a misnomer, surviving from 

 the misconceptions of earlier times. The Fern- Plant is neutral, being neither male nor 

 female, while it is on the prothallus that the sexual organs are borne. 



