THE FUNGI 187 



Order IV. Lycoperdineae 



The best known of the Gasteiomycetes are the Puffballs, of the 

 genus Lycoperdon (Fig. 152, A). The large fruits are globular, 

 oval, or pear-shaped solid bodies, often of large size. A section 

 through the young fruit shows a dense white mass of apparently 

 homogeneous tissue; but later there are formed many chambers 

 lined with the hymenium. As the fruit develops, the wall becomes 

 differentiated into a firm, somewhat leathery peridium, which in 

 the genus Geaster (Earth-star) is double. The sterile tissue 

 between the spore-chambers is partly composed of delicate cells, 

 which finally become completely disintegrated, and others whose 

 walls become hard and persistent, and form much-branched threads 

 (Capillitium), filling the interior as a loose, spongy mass mingled 

 with the ripe spores. At maturity, the peridium breaks, and the 

 powdery mass of spores is discharged. In Geaster (Fig. 152, B), 

 the outer peridium splits into strips, which bend back, exposing 

 the inner peridium, within which are contained the spores. The 

 outer peridium is strongly hygroscopic. 



Order V. Nidularineae 



The curious little Fungi of the genera Nidularia and Cyathus 

 (Fig. 152, D-F) differ from the Puffballs in having the spore- 

 chambers surrounded by a separate peridium, so that they form 

 little bodies, sp, lying within the open outer peridium, like eggs in 

 a nest, hence the popular name of Bird's-nest Fungi for these little 

 plants. 



LICHENS 



The remarkable group of Fungi known as Lichens do not con- 

 stitute a natural morphological group, as its members belong to 

 several widely separated orders of the Ascomycetes and Basidiomy- 

 cetes ; the greater part belonging to the former class. These Fungi 

 are intimately associated with certain low Algae or Schizophyceae, 

 upon which they are parasitic to a greater or less degree. The 

 Algae are completely included within the thallus, formed by the 

 mycelium of the Fungus, or in some of the gelatinous Lichens, like 

 Collema, the form of the Lichen is determined by the gelatinous 

 Nostoc-colony, which is the host of the Fungus. 



The Lichens were formerly ranked as a class coordinate with 

 the Algae and Fungi, it being supposed that the green cells, or 

 "gonidia," were outgrowths of the fungal hyphae. The researches 

 of De Bary and Schwendener first showed that the green cells were 



