2 hlenieiitary Botany 



through the water in which it floats. In this mode of motion 

 the Protococcus cannot be distinguished from many of the low 

 forms of animal hfe. 



A better distinction is to be found in the food that is assimi- 

 lated. Plants, like animals, require food ; but they, as a rule, 

 possess the power of obtainin|^ it from the mineral kingdom 

 only, whilst animals require for their food either vegetable or 

 animal substances. There are, however, exceptions to this 

 rule, and, as we have said, the two kingdoms appear to merge 

 gradually the one into the other in their lower forms. 



Botany, then, being the science which treats of plants, has 

 several branches. Morphology deals with the forms of the 

 organs of plants. Anatomy treats of their internal structure ; 

 and Histology of the minute appearance they present under the 

 microscope. Physiology deals with the functions of the various 

 organs, and the phenomena attendant upon life. Classification 

 has to do with the grouping of plants according to their relation 

 one to another. Geographical Botany deals with the distribu- 

 tion of plants in space ; and Palmontological Botany with their 

 distribution in time. Of these we shall omit the two latter 

 branches in the present work, merely taking up in an elemen- 

 tary form the remaining departments. 



