B. COMPARATIVE ANTIQUITY OF ALGAL SYMBIONTS 282
C. EVOLUTION OF PHYCOLICHENS 283 _a._ Gloeolichens _b._ Ephebaceae and Collemaceae _c._ Pyrenidiaceae _d._ Heppiaceae and Pannariaceae _e._ Peltigeraceae and Stictaceae
D. EVOLUTION OF ARCHILICHENS 287 _a._ Thallus of Pyrenocarpineae _b._ Thallus of Coniocarpineae _c._ Thallus of Graphidineae _d._ Thallus of Cyclocarpineae _AA._ LECIDEALES _aa._ Coenogoniaceae _bb._ Lecideaceae and Gyrophoraceae _cc._ Cladoniaceae 1. Origin of Cladonia 2. Evolution of the primary thallus 3. Evolution of the secondary thallus 4. Course of podetial development 5. Variation in Cladonia 6. Causes of variation 7. Podetial development and spore-dissemination 8. Pilophorus, Stereocaulon and Argopsis _BB._ LECANORALES _aa._ Course of Development _bb._ Lecanoraceae _cc._ Parmeliaceae _dd._ Usneaceae _ee._ Physciaceae
A. WORK OF SUCCESSIVE SYSTEMATISTS 304 _a._ Dillenius and Linnaeus _b._ Acharius _c._ Schaerer _d._ Massalongo and Koerber _e._ Nylander _f._ Müller-Argau _g._ Reinke _h._ Zahlbruckner
B. FAMILIES AND GENERA OF ASCOLICHENS 311
B. EXTERNAL INFLUENCES 357 _a._ Temperature _b._ Humidity _c._ Wind _d._ Human Agency
1. ARBOREAL 363 _a._ Epiphyllous _b._ Corticolous _c._ Lignicolous
2. TERRICOLOUS 367 _a._ On calcareous soil _b._ On siliceous soil _c._ On bricks _d._ On humus _e._ On peaty soil _f._ On mosses _g._ On fungi
3. SAXICOLOUS 371 _a._ Characters of mineral substrata _b._ Colonization on rocks _c._ Calcicolous _d._ Silicicolous
5. LOCALIZED COMMUNITIES 378 _a._ Maritime lichens _b._ Sand-dune lichens _c._ Mountain lichens _d._ Tundra lichens _e._ Desert lichens _f._ Aquatic lichens
D. LICHENS AS PIONEERS 392 _a._ Soil-formers _b._ Outposts of vegetation
A. LICHENS AS FOOD 395 _a._ Food for insects _b._ Insect mimicry of lichens _c._ Food for the higher animals _d._ Food for man
B. LICHENS AS MEDICINE 405 _a._ Ancient remedies _b._ Doctrine of “signatures” _c._ Cure for hydrophobia _d._ Popular remedies
D. LICHENS USED IN TANNING, BREWING AND DISTILLING 411
E. DYEING PROPERTIES OF LICHENS 411 _a._ Lichens as dye-plants _b._ The orchil lichen, Roccella _c._ Purple dyes: orchil, cudbear and litmus _d._ Other orchil lichens _e._ Preparation of orchil _f._ Brown and yellow dyes _g._ Collecting of dye-lichens _h._ Lichen colours and spectrum characters