sect, i CRYPTOGAMS 375 



but no poisonous effects have been proved. It was formerly employed in a salve 

 as a remedy for gout. Its fructification recalls that of the Discomycetous Mor- 

 cliella, but it has quite a different manner of development. A fructification of 

 this species of Phallus is about 15 cm. high. It has a thick, hollow stalk of a 

 white colour and is perforated with pores or chambers. Surmounting the stalk is 

 a bell -shaped pileus covered with a brownish - green gleba which, when ripe, is 

 converted into a slimy mass (Fig. 301). When young the fructification forms 

 a white, egg-shaped body, and is wholly enveloped by a double -walled peridium 

 with an intermedial gelatinous layer. Within the peridium (also termed 

 volva) the hyphal tissue becomes differentiated into the axial stalk and the bell- 

 shaped pileus, carrying the gleba in the form of a mass of hyphal tissue, which 

 contains the chambers and basidial hymenium. At maturity the stalk becomes 

 enormously elongated, and pushing through the ruptured peridium raises the pileus 

 with the adhering gleba high above it. The gleba then deliquesces into a dropping, 

 slimy mass, which emits a carrion-like stench serving to attract flies, by whose 

 agency the spores embedded in it are disseminated. 



Class XI 

 Liehenes (Lichens) 



The Lichens are symbiotic organisms (p. 213) ; they cons'ist of higher 

 Fungi, chiefly the Ascomycetes, more rarely Basidiomycetes, and uni- 

 cellular or filamentous Algae, Schizophyceae or Chlorophyceae, living in 

 intimate connection, and together forming a compound thallus or 

 consortium. Strictly speaking, both Fungi and Algae should be 

 classified in their respective orders ; but the Lichens exhibit among 

 themselves such an agreement in their structure and mode of life, that 

 it is more convenient to treat them as a separate class. 



In the formation of the thallus the algal cells become enveloped 

 by the mycelium of the Fungi in a felted tissue of hyphse (Fig. 

 302). The Fungus derives its nourishment saprophytically from the 

 organic matter produced by the assimilating Alga, without at the 

 same time behaving as a parasite and injuriously interfering with 

 its vegetative activity. The Alga, on the contrary, derives a definite 

 advantage from its consortism with the Fungus, receiving from it 

 inorganic substances and water. From the symbiosis entered into by 

 a Lichen Fungus with an Alga, a dual organism results with a distinct- 

 ive thallus, of which the form, which is influenced by the mode of 

 nutrition of the independently assimilating Alga, differs greatly from 

 that of other non-symbiotic Hyphomycetes with thalli consisting solely 

 of -profusely branched hyphas. 



In their adaptation to the requirements of the two constituent 

 members, the thalli of the Lichens exhibit a variety of forms which, 

 although sometimes made use of as a means of classification, are of no 

 value in indicating natural relationships. 



