PREFACE TO VOLUME II. 



THE present volume is devoted to a consideration of 

 the microscopic structure, the development, and the func- 

 tions of flowering plants ; that is, to their Vegetable His- 

 tology, Organogeny, and Physiology. In the first volume 

 of the Botanical Text-Book these topics were treated only 

 incidentally, or in an elementary manner, as an introduc- 

 tion to Morphology. 



Cryptogams, or flowerless plants, are treated in this 

 volume only so far as their study may throw light on 

 certain features of the anatomy and physiology of Phseno- 

 gams. The simple structure of many of the flowerless 

 plants, especially of those of the lower grades, makes them 

 suitable objects in which to investigate numerous phe- 

 nomena of vegetable nutrition, growth, and reproduction, 

 and they have been extensively employed as convenient 

 material for this purpose. Reference must therefore be 

 made in the present treatise to some of the more important 

 results. 



Vegetable Histology treats of the minute anatomy of 

 plants. A knowledge of its leading facts is indispensable 

 to a clear understanding of Vegetable Physiology, and 

 their presentation must needs precede any satisfactory 

 examination of the latter. The technique of Vegetable 

 Histology requires special treatment, and therefore con- 



