MODIFICATION OF ORGANS 171 



leaf, and performs utterly different functions, for 

 which indeed it is admirably adapted, but yet from 

 analogy must be % considered as homologous with a leaf. 



Then in chapters x and xi we learnt that stems 

 and roots are also capable of modification, so that dif- 

 ferent forms of these organs occur, and that their 

 different forms depend on the particular work each 

 has to perform. All this shows that we may, and 

 indeed to understand plants properly must, study their 

 organs from at least two different points of view. 

 We must try to find out first what any organ really 

 is, that is to say what it corresponds to in the normal 

 plant, whether to root, or shoot-portion (axis, stipule, 

 leaf, or leaflet), and secondly, why it has that particular 

 form, and what end the modification serves. 



The first of these studies is comprised in a special 

 branch of Botany termed morphology (the science of 

 form), the second is another branch termed physiology 

 (the science of nature and vital processes). 



Though distinct branches of study, these must be 

 taken to a certain extent together, for they mutually 

 assist each other, and any inquiry into the modifi- 

 cation in shape of an organ would be barren without 

 a knowledge of the physiological conditions. 



In the following pages of this chapter, a few com- 

 mon plants that can be found almost everywhere 

 in south India, are described with special reference 

 to some organ that is modified in some respect, and 

 the student is advised to examine actual living speci- 

 mens of as many as he can procure, and to follow 

 carefully the description given in each case. It can- 

 not be too consistently borne in mind that mere reading 



