2 MANUAL OF BOTANY. 



tion. 4. Geographical Botany is that which explains the laws 

 which regulate the distrilnition of plants over the surface of the 

 globe at the present time ; and 5. Palccontological or Fossil 

 Botany is that department which investigates the nature of the 

 plants Avhich are found in a fossil state in the different strata of 

 which the earth is composed.* 



Distinctions between Animals, Plants, and Minerals — 

 Botany being the science which treats of plants, we ought to 

 commence our subject by defining what we mean by a plant. 

 No absolute definition can, however, be given in the pi-esent li- 

 mited state of our knowledge. We have, it is true, no difficulty 

 in distinguishing a plant from a mineral; for the possession of 

 individual life and power of reproduction in the former, form 

 at once, without further investigation, a broad and well- 

 marked line of demarcation from the latter: and even Avhen we 

 compare a plant with an animal, so long as we confine our 

 researches to the higher members of the two kingdoms, the dis- 

 tinctions are evident enough; difficiilties only occur when we 

 look deeply into the subject, and compare together those bodies 

 which are placed lowest in the scale of creation, and stand as it 

 were on the confines of the two kingdoms. It is then that we 

 find the impossibility of laying down any certain characteristics 

 by which the two may be absolutely recognised : we shall at present, 

 therefore, only allude to those characters by which plants may in a 

 general sense be distinguished from animals, leaving the more 

 extended iuA^estigation of the subject to the pages of this volume. 



In the first place, Ave find that plants hold an intermediate 

 station between minerals and animals, and derive their nourish- 

 ment from the earth and the air by which they arc surrounded, 

 and that they alone have the power of converting inorganic or 

 mineral matter into organic. Animals, on tb.e contrary, consume 

 organic matter, and reconvert it into inorganic. In other words, 

 plants produce organic matter, and animals consume it. 



Secondly, plants are generally fixed to the soil, or to the 

 substance upon which they grow, and derive their food im- 

 mediately by absorption through their external surface; while 

 animals, being possessed of sensation and power of voluntary 

 motion, can wander about in search of the food which has been 

 prepared for them by ])lants, which they receive into an internal 

 cavity or stomach. Plants are, tlicrcfore, to be regarded as 

 destitute of sensation and power of voluntary motion, and as 

 being nourislicd from witliout; wliilc animals arc possessed of 

 those attributes, and arc nourished from within. 



* The first three departments are those only that come within 

 the scope of tlie ])rcscnt work; the latter being of too extensive 

 a nature to allow of bcin^ treated of satisfactorily within the 

 necessary limits of a student's manual. 



