4 BOTANY OF THE LIVING PLANT 



study of Plants in relation to their surroundings. The broadest of all 

 ecological conceptions is that Plants were in their ultimate origin 

 aquatic : that they have gradually emancipated themselves from 

 dependence upon an aquatic habitat : and that the highest terms 

 of the series are characteristically Dwellers on Dry Land. 



Conclusions like these have been drawn by Zoologists with regard 

 to the Animal Kingdom. Both branches of living things, viz. 

 Animals and Plants, probably originated in the water. Certain of 

 the very simplest Animals and Plants are so alike that it is difficult 

 to draw any line separating at such early stages the one Kingdom 

 from the other. It is therefore concluded that they probably had 

 a common origin, but that in the course of Evolution they diverged. 

 The most distinctive feature which separates them is that of Nutrition. 

 Plants advanced along the direct line of Self -Nutrition. They form 

 their own organic food from inorganic materials. These are ultimately 

 Carbon Dioxide and Water, together with Mineral Salts. Their green 

 colouring matter plays an essential part in the process of their 

 nutrition from such simple sources. Animals, on the other hand, 

 advanced along Predatory Lines. They take their food in more 

 elaborate form as material already organic : that is, either from bodies 

 which are living, or such as have been produced by living organisms. 

 This is seen both in Herbivorous and Carnivorous Animals. Pursuing 

 these divergent lines, both Animals and Plants established them- 

 selves upon exposed land-surfaces, and both show in their higher 

 terms abundant evidence of their fitness for living in the surroundings 

 which they have adopted. 



Since Animals take their food as organic material — that is, in 

 a sense at second hand, and do not construct it for themselves — it is 

 obvious that at some stage or other they are dependent for it upon 

 the Vegetable Kingdom. This gives Plants a special claim on the 

 attention of Biologists : for the Green Plant is, in point of fact, the 

 essential source of supply of organised material to all other forms of Life 

 upon the Earth' 's Surface. 



