Kelley — 94 — Mycotrophy 



Chalaud (1932) found tuber-formation in Seivardiella "in all re- 

 spects like the stem of other Metzgerias, especially Petalophyllum and 

 Fossomhronia." 



Denis (1919) found an endophyte in the chlorophylless thalli of 

 Aneura, and compared them to similar thalli known amongst lycopods. 



Mycothalli in Fern Gametophytes: — A description of the my- 

 cothallus in Opioglossiim pendulum is given by Lang (1902). Tissues 

 of the young prothallus are parenchymatous throughout, cells of the 

 lower portion contain an endophytic fungus while those of the upper 

 portion are free from it. Infection is usually through a rhizoid. 

 Superficial cells of the prothallus contain only infecting hyphae, the 



Fig. 5. — Section through an older mycothallus of Botrychium 

 obliquum. Shaded portion indicates the extent of region occupied by 

 endophyte, vicinage of reproductive organs being uninvaded {Redrawn 

 from Campbell, Ann. Bot. 35, pi. viii, fig. 12, 1921). 



fungus otherwise being confined to internal tissue. In older regions 

 of a branch the fungus occupies all the cells except for a superficial 

 zone of 1-2 layers. A number of vesicles are formed in a cell, often 

 close to the nucleus, while other cells contain thick coiled hyphae. 

 Plastids and chloroplasts occur in cells occupied by the fungus. The 

 European Ophioglossum vulgatmn mycothallus was described by 

 Bruchmann (1904). Infection is directly through the epidermal 

 cell- wall and hyphae spread through the mid-portion of the prothallus 

 but the outer cells are always fungus-free. Innermost cells are also 

 fungus-free and contain starch. Nuclei of infected cells increase in 

 volume while hyphae coil in the cells and form an irregularly shaped 

 structure: vesicles occur in older portions of the prothallus. The in- 

 fected portion forms in effect a cylinder which is particularly well 

 developed about the sexual organs. 



Campbell (1907) in general confirms Lang's description of 

 prothalli in Ophioglossum, and in the appendix of his Mosses and 



