Lecture XV III. 143 



cells, their entrance is constricted to a narrow pore or stoma. 

 On each side of the stoma is a curved cell, a guard-cell, reminding 

 one of the similar apparatus round the pore leading into the 

 photosynthetic chambers of Marchantia. But it must be re- 

 membered that those pores are structures in the gametophyte, 

 while the stomata of Funaria belong to the sporophyte. It may 

 be remarked here that stomata having the structure of this type 

 are only found on sporophytes, and they occur with very little 

 modification on the sporophytes of all the higher plants. With 

 this photosynthetic organ, the sporophyte of Funaria in its later 

 stages must be almost, or completely, independent of the gameto- 



MARCHANTIA 



' Sporophyte 



[Minute stalked sporandiurrH 

 L * Parasite .. I 



/ 



Oosperm 



/ N. > ^^ 



Sperm Ovum Spore Spore 



Anrheridium Archegonium 

 Antheridiophore Archecjoniophore 



'Female Gametophyte 



'Male Gametophyte 



[Creeping thallus with photosynthetic 7 

 / chambers, scales & rh Isolds . HolophyticJ 



FIG. 30. Diagram summarising the life-history of Marchantia. 



phyte, so far as its carbon supply is concerned. Apparently 

 however, for all other substances it is dependent on the gameto- 

 phyte. Hence, its parasitism is not quite so complete as the 

 sporophyte of Marchantia. 



The life-histories of Funaria and Marchantia may be summarised 

 by the two schemes shown in Figs. 30 and 31. 



The formation of buds on theprotonema and upon the rhizoids 

 is a very prolific method of asexual reproduction. Such repro- 

 ductive rhizoids are usually formed on the lower parts of the stem 

 but they may arise from almost any part of the gametophyte, 

 especially from the detached parts kept in a moist atmosphere. 



