^^\i;40 



PREFACE 



A few centuries ago people believed that the earth was created 

 suddenly, and that plants and animals were created just as they are 

 today; but no one with any scientific training now believes in such 

 an origin of the earth or its inhabitants. The first living things were 

 simple and, in some way or another, originated from non-living mat- 

 ter. Such simple forms gradually developed into more and more com- 

 plex organisms. No one believes that any organism as complex as a 

 fern, or even as complex as a moss or liverwort, ever developed di- 

 rectly from non-living matter; they came from simpler forms. We 

 may take it as a fact that the plants and animals on the earth today 

 are the lineal descendants of plants and animals which lived hun- 

 dreds of millions of years ago. Line after line of these ancient forms 

 became extinct; but, here and there, an individual varying in some 

 way from the main line, with some variation which made it able to 

 withstand changing conditions which were fatal to its neighbors, sur- 

 vived and became the progenitor of a new race. 



Consequently, if we are to understand the gymnosperms, or any 

 other great group of plants, we should study not only those which 

 exist today, but also those extinct ancestors whose fragmentary rec- 

 ords can be read in the rocks. And beyond the available records, we 

 should try to imagine the missing parts of the life-histories, and try 

 to picture to ourselves the still more ancient progenitors. 



Since this book is intended to be of service not only to those 

 who would gain some knowledge of the gymnosperms, but also to 

 those who would go farther and do productive research in this great 

 group, a few admonitions may be helpful. 



Read, and read widely, that you may know what has already been 

 accomplished; and read critically. But no one can read critically 

 whose knowledge comes entirely, or even principally, from reading. 

 You must have a first-hand knowledge of the material, must study it 

 in the field and in the laboratory. The student who has not had 

 sufficient experience to make a first-class preparation for microscopic 



