PART III. 



ORGANS AND SYSTEMS OF 

 ORGANS- 



"When any given organ develops similar or dissimilar lateral 

 organs we speak of the entire structure as an organ-system. In 

 such a system there are members of different order and members of 

 different rank. Members are of a different order when they have 

 a different origin. The rank of different members is dependent 

 upon a physiological inequality ; for example, aerial members with 

 green leaves and subterranean storage-tissue with scaly leaves are 

 physiologically different. 



We shall now treat (1) of the morphological and physiological 

 differences of organs, (2) of the origin and arrangement of lateral 

 organs and the causes of such arrangement, (3) of the difference in 

 the development of the members of a system of similar organs 

 (branching), which will finally lead us to the discussion of inflores- 

 cence. Although I have taken exception to NAGELI and SCHWEN- 

 DENER in the interpretation of fundamental principles, yet the gen- 

 eral treatment of the subject matter in Part III is adapted from the 

 works of the authors mentioned. As to the descriptive morphology, 

 I shall adhere to RADLKOFER'S method 'of treatment, and more espe- 

 cially to that of G. "W. BiscHOFF. 1 



I. THE MORPHOLOGICAL AND PHYSIOLOGICAL 

 RELATIONS OF ORGANS. 



A. THE PRINCIPAL FORMS OF ORGANS. 



In the course of this discussion we will find that it is neces- 

 sary to add physiological properties to the fundamental morpholog- 



1 Hanclbuch der botanischen Terminologie. 



155 



