185 



as in 0. moluccanuin and 0. pendulum, the definitive axis of 

 the adult sporophyte is formed secondarily, the primary 

 shoot derived from the embryo having only a limited 

 growth. While probably only an analogy, it is worth consi- 

 dering, as showing a tendency at least to a similar course 

 of development in the sporophytes of the two genera. 



THE SIGNIFICANCE OF THE ENDOPHYTE. 



There has been some question as to the exact role of the 

 endophyte in the economy of the plant. That it is essential 

 to the development of the pro thallium is shown by the history 

 of the germination of the spores. Where the connection with 

 the fungus is established, the growth is accelerated, and the 

 further development of the gametophyte is made possible, while 

 in no cases is it al)le to develop without this association. In 

 the latter case the young gametophyte perishes after the 

 reserve food in the spore is exhausted. 



It is probable that the principal role of the fungus is in the 

 assimilation of the organic constituents from the humus. In a 

 subterranean chlorophylless gametophyte photo-synthesis is of 

 course out of the question, and the carbon compounds must 

 be obtained from the organic matter in the humus. It is 

 probabl}^ in this connection that the symbiotic activity of the 

 fungus comes into play. Just how this is accomplished must 

 be determined by experiment. 



It is not probable that the fungus plays any important part 

 in the actual absorption of food elements from the soil. It is 

 rather in the metabolic processes within the thallus that the 

 fungus is especially useful. Bruchmann (tJber das Prothallium 

 und die Sporenpflanze von Botrychinra Lunaria, Flora 96:211, 

 1906) thinks that the great amount of oil developed b}^ the 

 endophyte is probably of use as a protection against dessication 

 to which the prothallium may be exposed. The writer found 

 that the prothallia of 0. pendulum ^could be quite dried up for 

 a short period without being killed, but as this is also true of 

 certain green fern prothallia, e. g., Gymnoyramme irianc/ularit, 



Ann. Jard. bot. Biiitcnz 2e Ser. Vol, VI. 13 



