TABLE OF CONTENTS 



Vol. 40 



I. The Huron River valley . 351 



Physiographic features 351 



Physiographic history 353 



Forests . . . 355 



Meteorological conditions 356 



II. The bogs : their development and ecological conditions .... 360 



Physiographic origin of the lake and bog basins . . . . . . 360 



Bog and lake vegetation 362 



The processes involved in peat formation 367 



The physical and chemical properties of peat 372 



The bog as a habitat for plants 418 



A. Physical factors 418 



1. Wind 418 



2. Temperature 419 



3. Texture 422 



4. Mechanical properties v , . . 423 



5. Diffusion properties 423 



6. Water capacity 424 



7. Osmotic pressure 424 



B. Chemical factors 425 



1. Ground water . . . .'.." . . 425 



2. Acidity 426 



3. Food material . 427 



C. Biotic factors 428 



III. The bog - plant societies 429 



West lake 430 



First Sister lake 432 



Bog north of Delhi 436 



Bog near Oxford, Oakland county 439 



The Delhi muskeags 441 



Bog on Carpenter road 441 



The Chelsea bog 444 



General consideration of the bog flora 447 



Vol. 41 



IV. The ecological characteristics of the bog flora and their causes . . 17 



Experiments 22 



Water cultures 24 



V. Summary 34 



Bibliography 40 



