PLANT LIFE. 



CHAPTER I. 



GENERAL IDEAS OF PLANT LIFE. 



Life — Characteristics of Living Matter — Protoplasm — Relation of Life 

 to Surroundings — Protection — Division of Labour — The Cell, the 

 only Unit of Plant Structure — Formation of Cells — Tissues — 

 Chlorophyll — Starch — Shadowing in of the Vegetable Kingdom — 

 Asexual and Sexual Modes of Reproduction — Gradual Evolution 

 and Advantages of the Sexual Mode of Reproduction — Advantages 

 and Disadvantages of Plant Life compared with Animal Life in the 

 Struggle for Existence — Primary Groups of Plants p. \ 



From the present standpoint of knowledge a concise and 

 intelligible definition of life is not possible. This statement 

 must not be interpreted as implying the absolute impos- 

 sibility of ever attaining to this point ; on the other hand, 

 every new discovery strengthens the idea that the existence 

 and continuance of life is governed by natural laws. For 

 example, the manifestation of life depends on the presence 

 of a definite substance called protoplasm, the existence of 

 which in turn depends on surroundings ; in other words, so 

 long as protoplasm retains its individuality life is manifested, 

 whereas the moment this individuality is destroyed, due to 

 the predominance of antagonistic forces, life is no longer 

 present. Heat above a certain degree, as also electricity, can 



