PREFACE 



This book has been prepared for students of the biological sciences 

 who desire a means of becoming more readily acquainted with the litera- 

 ture and problems of cytology. It does not pretend to be an exhaustive 

 treatise for the use of experienced cytologists, though it is hoped that to 

 them also some of its features may be of service. 



For a number of years students of biology, especially those working 

 along botanical lines, have been faced with the task of searching through 

 a widely scattered literature for information on various cytological 

 subjects. It is the purpose of this book not to render the consultation 

 of that literature unnecessary, but only to make it easier; the student 

 can scarcely be too strongly urged to derive his information from original 

 sources wherever possible. The author does not presume to replace, but 

 rather aims to supplement, Professor Wilson's well known book, The 

 Cell in Development and Inheritance, which, though written twenty years 

 ago and with the emphasis primarily on the zoological side, will remain 

 invaluable to all workers for many years to come. The more recent 

 works of Gurwitsch (Morphologie und Biologie der Zelle), Heidenhain 

 (Plasma und Zelle), and Buchner (Prakticum der Zellenlehre) are of im- 

 portance especially to the zoologist. 



The living cell, or protoplast, which represents the organized proto- 

 plasmic unit of structure and function, obviously cannot receive complete 

 description in structural terms. Until a comparatively recent period 

 cytological researches dealt primarily with cell structure, including 

 particularly the conspicuous changes undergone by this structure in 

 connection with the reproduction of the cell (cell-division) and of the 

 multicellular organism (maturation and fertilization) . A gradual shifting 

 of emphasis has since led to the opening of fruitful fields in other direc- 

 tions, and the important results already achieved have shown with increas- 

 ing clearness the need for a closer acquaintance with the physiological 

 aspects of cell activity, not only in metabolism and growth, but also in 

 the reproductive phases of the life cycle. The present work, though 

 dealing mainly with the structural aspects of the subject, may aid indi- 

 rectly in fulfilling the above need by making the prerequisite data of cell 

 morphology more readily available. 



Throughout the book, which in many of its chapters treats chiefly 

 of the plant cell, attention is focussed upon the protoplast : the cell wall 

 is given only brief consideration, since it plays a relatively minor role in 

 the processes of particular interest to the cytologist at the present time. 



