PRIMITIVE TYPES. 63 



extent its supremacy over the previously existing forces, is 

 not as yet formulated ; and yet it is not difficult to under- 

 stand why a mass of living organic matter should not possess 

 more energy than an equal mass of typical inorganic matter 

 from chemical and physical laws. It will be sufficient to 

 allude to the chemical side only. The amount of energy 

 liberated by matter is very much influenced by its relative 

 chemical stability ; inorganic matter is as a rule compara- 

 tively stable, that is, its chemical composition is not dis- 

 turbed by the ordinary surroundings ; whereas organic matter 

 is exceedingly unstable or constantly changing within certain 

 limits, as illustrated by the chemical changes constantly exer- 

 cised by the protoplasm, chlorophyll, etc., on food, and the 

 further chemical manufacture of the numerous organic 

 substances present in plant and animal tissues. This 

 incessant change, due to chemical instability, results in the 

 generation of energy recognized as heat, electricity, etc. 

 Whether the balance and mutual action of this energy, 

 generated by the instability of organic matter, constitutes 

 life is not known. 



Hovering round the Flagellata are numerous groups of 

 organisms that are considered as showing in a very incipient 

 stage those special structures that in more highly evolved 

 plants are considered characteristic of the Vegetable 

 Kingdom. Amongst the earliest of differentiations observable 

 is the formation of chlorophyll, which indeed is the key-note 

 of plant life, inasmuch as the power of assimilating inorganic 

 food by plants depends on the presence of chlorophyll ; and 

 this power of utilizing inorganic food, followed by the form- 

 ation of starch, and the firm, permanent cellulose cell-walls, 

 are the characteristics of plant life. It is however important 

 to bear in mind that the three characteristic features of 



