AUTHORS' PREFACE. 



THE present volume, as appears from the title, is a new edition of the second 

 book of Sachs' Text-book of Botany (from page 235 to page 634 of the 4th 

 Edition), and has been undertaken by me at the desire of Professor Sachs. In 

 fulfilling this task I have considered it my business to make those changes only, 

 which seemed to me to be required by the literature which has appeared since 

 the year 1873 and by the results of my own investigations. That these changes 

 are sometimes not inconsiderable will surprise no one who has followed the almost 

 superabundant labours of the last few years in this particular portion of botanical 

 study. But in presence of these changes I desire specially to remind my readers 

 of the large amount of original research which was first communicated to the world 

 in Professor Sachs' Text-book, especially in connection with the Vascular 

 Cryptogams. The present Edition is also indebted to him for the majority of all 

 such additional illustrations as are not copies from other authors, or, like figures 17, 

 18, 95, 101, 112, 153, 208, 223, 239, 240, 241, 259, 297, have been supplied by 

 myself. 



The task of explaining the connection between the several groups has been 

 rendered difficult by the present state of the terminology, which is one of transition. 

 We may hope however that the terminology will soon be greatly simplified and 

 cleared up by applying the acknowledged homologies, and that we shall no longer call 

 the same object in one place a ' placenta,' in another a ' receptacle ' or a ' columella,' 

 or use the term ' frons ' for the thallus of a Marchantia or a Pellia, or apply the 

 term pro-embryo alike to the protonema of the Mosses, the prothallium of Ferns, 

 and the suspensor of Spermaphytes. I have entirely avoided such antiquated 

 expressions as ' corpusculum ' for the archegonium of Gymnosperms, and unmeaning 

 terms like ' Rhizocarps ' to designate the Heterosporous Filices, and in connection 

 with the sporangia (including pollen-sacs and ovules) I have endeavoured to carry 

 out the terminology proposed by myself and resting on the homology as established 

 in the development of these organs. Accordingly I use the term archesporium in all 

 cases, even in that of the sporogonia of the Muscineae, to designate the cell, cell-row 

 or cell-layer in which the spore-producing tissue originates, and unlike other writers 

 I apply the same term also to the ' mother-cell of the embryo-sac.' I use the 

 expression ' tapetal cells,' as will be seen in the text, in a narrower sense than 

 that adopted by some authors. 



The manuscript was completed in January of the present year, and I have 

 therefore been unable to make use of several interesting publications which have 

 appeared since that date. 



K. GOEBEL. 



ROSTOCK, August, 1882. 



