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 506 
Helpful Bacteria 316 
XXI. Saprophytism and Symbiosis 321 
Saprophytism . . '. 322 
Symbiosis 324 
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 
Metachlamydeae (Sympetalae) 473 
