INTRODUCTION 



HflNHB 



Figure 3 

 Cephalodia of Peltigera aphthosa: Diagram 1, a, a young cephalodium; b, the trichomatic 

 hyphae holding the cephalodium. Diagram 2, an older cephalodium; a, the internal hypae and 

 algal cells; b, the well-developed cortex; c, the supporting trichomatic hyphae. Diagram 3, a 

 mature cephalodium; a, the internal hyphae and algal cells; b, the upper cortex; c, the lower cor- 

 tex; d, the supporting hyphae; e, the thallus below the cephalodium, where the algal cells have 

 disappeared and the cortex is transformed into hyphal tissue; /, the cortex; g, the algal layer of 

 the supporting thallus. Diagram 1, enlarged about 100 diameters; diagram 2, enlarged 400 diam- 

 eters; diagram 3, enlarged 200 diameters. From Schneider. 



