THE FUNGI. 145 



stituents ? The production of the spores is a result of a 

 conjugation, the study of which is too difficult for begin- 

 ners. Male gametes, spermatia, conjugate with female 

 gametes, trichogynes, inside the tissues of the hyphre. 

 The resulting apothecia emerge to the surface, where the 

 spores are exposed directly to the open air in gymno- 

 carpous Lichens, or are ejected through minute orifices in 

 the angiocarpous Lichens when the dried apothecium is 

 wet. 



The spores germinate into hyphse, but this development 

 soon ceases and the hyphse die, unless they come in con- 

 tact with cells of the Algae with which they are associated 

 in forming the Lichen. When the hyphae and the Algse 

 come together, the development of each goes on vigor- 

 ously. The Algse, protected and furnished moisture by 

 the Fungus, take in carbon dioxide from the air and 

 mineral elements from the moisture. The rhizines of the 

 Fungus, in the case of many foliaceous Lichens, take up 

 mineral matters from the substratum, and even decom- 

 pose the substance of rocks and convey to the Algse the 

 inorganic materials necessary for the formation of proto- 

 plasm. As the protoplasm increases, the cells enlarge 

 and multiply by cell division. At the same time the 

 parasitic Fungus draws abundant sustenance from the 

 well-nourished cells of the Algae. 



8. Besides the reproduction by spores, there is also a 

 vegetative reproduction by means of soredia. Select a 

 specimen of Usnea barbata that bears few or no apothecia, 

 and that appears powdery at least in places. Material 

 secured as soon as it has dried after a rain is best. Brush 

 some of the powder into a drop of water on a slide, and 

 examine under high power. Single algal cells and groups 

 of algal cells associated with fungal hyphse will be seen. 

 These are the soredia in their elementary stages. More 

 advanced stages will also be found. In these the hyphse 

 CLARK'S BOX. 10 



