TABLE OF CONTENTS 

 The Tree as an Invention, Charles D. Stewart 172 



What Are The Most Remarkable Trees?, Henry D. 



Ticmann I77 



Tree-rings and History in the Western United States, 



Edmund Schulman 182 



PART THIRTEEN 



CONSERVATION 191 



The Conservation of Wild Flowers, Robert B. Gordon 192 



What Worth Wilderness?, Paul B. Sears 197 



Wasteland, Marya Mannes 200 



PART FOURTEEN 



PALEOBOTANY 203 



Redwoods Around the Pacific Basin, Ralph W. Chancy 204 



Origin, Nature and Uses of Coal, Allan Sherman and 



Allen B. MacMurphy 207 



Introduction to Pollen Analysis, G. Erdtman 209 



The Study of Fossil Plants, Anonymous 212 



PART FIFTEEN 



CYTOLOGY 217 



The Periodic Reduction of the Number of the Chromo- 

 somes in the Life-history of Living Organisms, 



Eduard Strasburger 218 



The Cell as a Structural Unit, George A. Baitsell 222 



Cytology: the Study of the Cell, Ralph E. Cleland 227 



What Is A Gene?, G. W. Beadle 238 



Cytotaxonomy, Edgar Anderson 241 



