XV111 CONTENTS 



CHAPTER PAGE 



XVIII. Life Histories of Algae (concluded) 242 



Dictyota dichotoma 242 



Ulothrix 250 



Pleurococcus 252 



XIX. Life Histories of Fungi 256 



An Alga-like Fungus (Rhizopus) 256 



A Sac-fungus (Microsphaera) 268 



A "Rust" Fungus (Wheat Rust). 272 



A Fleshy Fungus (Agaricus) . . . ^ 276 



Other Non-green Plants 284 



XX. Economic Importance of Fungi 288 



Fungi that cause Plant Diseases 290 



Molds 304 



Cold Storage 305 



Yeasts 306 



Bacteria 306 



Helpful Bacteria 316 



XXI. Saprophytism and Symbiosis 321 



Saprophytism 322 



' Symbiosis . . 3 24 



XXII. The Problem of Sex in Plants 344 



XXIII. From Alga to Fern 362 



XXIV. Calamites and Lycopods 368 



I. The Horsetails (Equisetales) 368 



II. The Club-mosses (Lycopodiales) 376 



III. Little Club-mosses (Selaginellales) ..... 382 



XXV. Seed-bearing Plants .390 



The Cycads 390 



XXVI. Seed-bearing Plants (continued) 412 



Gymnosperms 412 



Life History of the Pine 412 



Reproduction 416 



XXVII. Seed-bearing Plants (continued) 433 



Life History of an Angiosperm 433 



XXVIII. Seed-bearing Plants (continued) 446 



Angiosperms 446 



Archichlamydeae 457 



Apetalae 457 



Polypetalae 459 



XXIX. Seed-bearing Plants (continued) 473 



Metachlamydese (Sympetalae) 473 



