THE FUNGI: ASCOMYCETES AND BASIDIOMYCETES 331 



Gelatinization now commences, beginning just below the interhyphal 

 spaces and spreading down towards the base of the knot in an inverted dome. 

 The tissue in the inside of this zone is formed of small-celled filaments from 

 which the gleba becomes developed, while the outer tissues constitute the 

 peridium. 



As growth continues the peridium becomes differentiated into three layers. 

 The outer layer or exoperidium is made up of loosely interwoven, longi- 

 tudinally running filaments which give rise externally to numerous septate 

 hairs. The inner layer or endoperidium is broad and is composed of 

 gelatinized filaments which extend inwards to the gleba. Between these two 

 layers there is a middle zone consisting of a pseudoparenchyma. It should 



Peridiole 



Basidiospores 

 Funiculus 



Fig. 326. — Cyatlius striatus. Vertical section through 

 a peridiole to show the internal cavity lined with 

 basidia and the stalk by which the peridiole is 

 attached to the wall of the fruiting body. 



be noted that it is partly on the structure of the peridium that the genera 

 of the Nidulariaceae are separated. In Nididaria the peridium consists of a 

 single laver, in Cnuibiihim there are two layers, the exoperidium and the 

 endoperidium, while in Cyathiis a third layer is differentiated. 



While the development of the peridium continues, the gleba also under- 

 goes differentiation, and circular areas are formed composed of zones of 

 densely interwoven hyphae, each of which later forms a separate, flattened, 

 plate-like body, the peridiole (Fig. 326). As growth continues the peridiole 

 enlarges and a space appears at the centre which is at first filled with a 

 gelatinous material, probably produced by the dissolution of the central 

 hyphae. This internal cavity gradually assumes an oval shape, enlarges, and 

 is finally lined by a definite palisade layer composed of hyphae with swollen 



