14 INTRODUCTION. 



kind of life with which it is endowed, the organization through 

 which its hfe is manifested ; — in other words, how the plant lives 

 and grows, and fulfils its destined offices. This is the province of 

 PHYSIOLOGICAL BOTANY. This department of the science 

 naturally divides into two hranches, namely, Structural Botany and 

 Vegetable Physiology, which arise from the different views we may 

 take of plants. The study of their organization belongs to Struc- 

 tural Botany, Avhich includes every inquiry respecting their 

 structure and parts. And this may again be divided into two 

 branches, viz. : — 1st, Vegetable Anatomy, or Phytotojiy, the 

 study of the minute structure of vegetables as revealed by the 

 microscope ; and 2d, Organography, the study of the organs or 

 consj^icuous parts of plants, as to their external conformation ; in- 

 cluding Morphology (the study of forms), which relates to the 

 conformation and the symmetrical arrangement of these organs, 

 and the modifications they undergo, either in different species, 

 according to the conditions of their existence, or in the same indi- 

 vidual in the course of its development, — a department analogous 

 to what is termed Comparative Anatomy in the animal kingdom. 

 Thus in Structural Botany, whether we regard the external con- 

 formation or the minute internal structure, the plant is viewed as 

 a piece of machinery, adapted to the accomplishment of certain 

 ends. On the other hand, the study of this apparatus in action, 

 endowed with life, and fulfilling the purposes for which it was in- 

 tended, and also of the forces which operate in it and by it, is the 

 province of Vegetable Physiology. 



4. The subjects which Physiological Botany embraces, namely. 

 Vegetable Anatomy, Organography, and Physiology, therefore, 

 spring naturally from the study of vegetables as individuals, — 

 from the contemplation of an isolated plant throughout the course 

 of its existence, from gennination to the flowering state, and the 

 production of a seed hke that from which the parent stock origi- 

 nated. These branches would equally exist, and would form a 

 highly interesting study (analogous to human anatomy and physi- 

 ology), even if the vegetable kingdom were restricted to a single 

 species. 



5. But the science assumes an immeasurably broader interest and 

 more diversified attractions, when Ave look upon the vegetable crea- 

 tion as consisting, not of wearisome repetitions of one particular form, 

 in itself however perfect or beautiful, but as composed of thousands 



