Plant Anatomy - libro nuevo

PLANT ANATOMY FROM THE STANDPOINT OF THE DEVELOPMENT AND FUNCTIONS OF THE TISSUES AND HANDBOOK OF MICRO-TECHNIC BY WILLIAM CHASE STEVENS PROFESSOR OF BOTANY IN THE UNIVERSITY OF KANSAS FOURTH EDITION, REVISED WITH 155 ILLUSTRATIONS LONDON J. A. CHURCHILL 7 GREAT MARLBOROUGH STREET 1924 PLANT ANATOMY STEVENS PREFACE TO THE FIRST EDITION To one interested in biology the study of plant anatomy affords a rich and alluring field, since it reveals how plants, under conditions the most exacting, have met and solved the problems of their existence by achieving the power and habit of cell differentiation and cell association into tissues adapted to carry on the different physiological functions and when the study of plant anatomy is directed to reveal the process of cell differentiation and the steps by which the mature tissues are made fit for their functions, the student cannot fail to see at once its high biological significance. The ontogeny and physiology of the tissues is in fact so illumi nating to their mature form and structure that the student of anatomy works to a distinct disadvantage if he is not constantly reverting for enlightenment to questions of origin and function and whatever motive may incite him to the study of plant anatomy, whether it be purely intellectual curiosity or the recognition of the necessity of a knowledge of plant anatomy to the scientific pursuit of pharmacognosy or agriculture, he will find the outcome more worthy of his efforts if he has sought out the physiological and ecological interpretation of his anatomical findings. It is not natures way to evolve cells and tissues at random, with no problems to be solved by their evolution. The tissues are not anaimless expression of the power of variability. Rather they represent the means of the triumph of living organisms over the conditions and forces which make up their environment. This book attempts to point out in a brief and elementary way how plants arrive at this achievement by the evolution of the different physiological tissue systems from a primitive, undifferentiated embryonic tissue, and how the tissue systems are adapted by their character and relation to each other to Vlll PREFACE TO THE FIRST EDITION carry out the plants vegetative functions. It seeks to answer in some measure questions about what kind of organisms plants are how they wrest their living from the inorganic world and how they are equipped to make satisfactory terms with their environment. At the close of each chapter are given directions for obser vations that will afford a good foundation for critical discussion. In carrying out the work as there outlined the student will become familiar with the most important practices in micro technic, and he will at the same time get training in independent work that will prove a significant part in his education. Chap ters dealing in sufficient detail with microtechnic and micro chemistry are given to help the student to pursue the subject beyond the limits of this book, and to undertake practical work in pharmacognosy and pure food and drug investigations. In the illustrations much use has been made throughout the book of generalized diagrams. I have found these very helpful in my teaching, and I offer them here in the hope that they may prove suggestive to students in correlating and interpreting the details of the isolated sections with which the histologist has todeal, and of service in throwing light on the operation of the physiological functions. I must make acknowledgment of especial indebtedness for substance and point of view to Strasburgers Botanisches Prac ticum, and Leitungsbahnen, Haberlandts Physiologische Pflan zenanatomie, Pfeffers Physiology of Plants, Zimmermanns Microtechnic, Czapeks Biochemie der Pflanzen, Meyers Grundlagen and Methoden fur die Mikroscopische Untersuch ung von Pflanzenpulvern, Chamberlains Methods in Plant Histology, and Wintons Microscopy of Vegetable Foods...