CHAPTER VII. THE THALLOPHYTA. 307 



sometimes quite a large number of them in one carpogonium. 

 The spores thus produced are called carpospores. 



In some cases, as in Nemalion, fertilization results in the 

 out-growth of several branches from the basal part, which break 

 up into cells, each one of which becomes a carpospore. In other 

 cases, as in Lejolisia, the stimulant influence results in the devel- 

 opment of adjacent cells to form filaments which grow up around 

 the fertilized cell, and unite laterally to form an envelope to 

 enclose the spores, which, in the meantime, are formed by the 

 division of the fertilized cell. Both the sexual and asexual pro- 

 cesses in this plant are illustrated in Figs. 506 and 507. 



CHAPTER VII. — The Thallophyta (Continued). 

 CLASS IV.— THE FUNGI. 



The Chytridie^e — The Ustilagxie^e — The Phycomycetes — 

 The Ascomycetes. 



The Fungi are, in their habits, chlorophylless saprophytes or 

 parasites. In all but a few instances their vegetative parts con- 

 sist of slender segmented or unsegmented usually colorless fila- 

 ments, called hyphae, which ramify among decaying organic 

 debris, or invade the tissues of living organisms, plant or animal, 

 and derive their nourishment from them. The only members 

 which do not produce hyphae are some of the lowest Fungi 

 belonging to the Chytridieae and certain degenerate higher forms, 

 such as the Yeast-plant. Here the whole vegetative portion of 

 the plant consists of rounded cells or chains of cells. In the 

 higher Chytridieae, however, some of the cells emit slender 

 branches, which may be regarded as rudimentary hyphae. 



In the simpler hyphal forms, the hyphae occur singly or more 

 or less interwoven into a tangled felt-work, but they are not 

 gathered into definite forms, and have little or no dependence 

 upon each other ; in the higher groups, however, there is more or 

 less division of labor among the hyphae, and they become con- 

 solidated into false tissues, which acquire definite shapes accord- 

 ing to the species. Of this character are the fructifying organs 



