IV 



CHAPTER IV. 

 THE GROWTH, MECHANICS AND CHEMISTRY OF LICHENS. 



INTRODUCTION II. GROWTH OF THE APOTHECIA . . 75 



I. THE GROWTH OF THE THALLUS. 71 III. THE DEVELOPMENT AND STRUC- 



1. The Protothallus (Hypothal- TURE OF THE SPORES ... 77 

 lus, Promycelium) . . . 71 IV. GROWTH OF THE ALGAE . . . 78 



2. Development of the Thallus. 72 V. THE SPERMAGONIA . So 



(a) Horizontal Growth. VI. MECHANICAL ADAPTATIONS . . . Si 



(6) Vertical Growth. VII. THE CHEMISTRY OF Li CHENS 84 



(c) Intercalary Growth. 



CHAPTER V. 



REPRODUCTION AND PROPAGATION OF LICHENS. 

 I. THE SPORES 87 II. THE SOREDIA AS PROPAGATIVE 



1. The Ejection and Distribu- ORGANS 92 



tion of Spores ... . . 87 III. VEGETATIVE PROPAGATION ... 93 



2. The Germination of Spores 89 IV. LIFE-PERIOD OF LICHENS . 94 



3. Spores as Organs of Repro- 

 duction 90 



CHAPTER VI. 



THE POLYPHYLOGENY OF LlCHENS. 



INTRODUCTION 96 2. Chroolepus ( Trentopohlia ) 



I. THE FUNGAL TYPES 97 umbrina 100 



1. The Pezizaceae 98 3. Pleurococcus vulgaris . . . 100 



2. The Patellariaceae 98 4. Dactylcococus infusionum . 100 



3. The Phacidiaceae .... 98 5. Nostoc commune 100 



4. The Stictidaceae 99 6. Rivularia nitida 101 



5. The Sphaeriaceae .... 99 7- Polycoccus punctiformis . . 101 

 II. THE ALGAL TYPES 99 8. Gloeocapsa polydermatica . 101 



i. Cystococcus humicola ... 99 9- Sirosiphon pulvinatus . . . 101 



PART II. 

 THE CLASIFICATION AND SPECIAL MORPHOLOGY OF LICHENS. 



CHAPTER I. 



A SYSTEM OF CLASSIFICATION. 

 I. INTRODUCTORY CONSIDERATIONS. 102 II. CHEMICAL REACTIONS . . . . 106 



CHAPTER II. 

 DESCRIPTIONS OF THE FAMILIES AND GENERA. 



INTRODUCTION. 108 3. Calicium . . .114 



GENERAL DESCRIPTION OF THE 4. Cyphelium . . .115 



PLATES . . no 5. Acolium 115 



KEY TO THE FAMILIES 109 6. Sphaerophorus ... .117 



I. CALICIACEAE no II. CLADONIACEAE 118 



1. Mycocalicium 112 i. Baeomyces 120 



2. Coniocybe 112 2. Pilophoron 122 



