The Story of Evolution 63 



microscopic globules of living matter, not unlike the simplest 

 bacteria of to-day, but able to live on air, water, and dissolved 

 salts. From such a source may have originated a race of one- 

 celled marine organisms which were able to manufacture chloro- 

 phyll, or something like chlorophyll, that is to say, the green 

 pigment which makes it possible for plants to utilise the energy 

 of the sunlight in breaking up carbon dioxide and in building up 

 (photosynthesis) carbon compounds like sugars and starch. 

 These little units were probably encased in a cell-wall of cellulose, 

 but their boxed-in energy expressed itself in the undulatory 

 movement of a lash or flagellum, by means of which they pro- 

 pelled themselves energetically through the water. There are 

 many similar organisms to-day, mostly in water, but some of 

 them simple one-celled plants paint the tree-stems and even 

 the paving-stones green in wet weather. According to Prof. A. 

 H. Church there was a long chapter in the history of the earth 

 when the sea that covered everything teemed with these green 

 flagellates the originators of the Vegetable Kingdom. 



On another tack, however, there probably evolved a series 

 of simple predatory creatures, not able to build up organic matter 

 from air, water, and salts, but devouring their neighbours. These 

 units were not closed in with cellulose, but remained naked, with 

 their living matter or protoplasm flowing out in changeful pro- 

 cesses, such as we see in the Amoebas in the ditch or in our own 

 white blood corpuscles and other amoeboid cells. These were the 

 originators of the animal kingdom. Thus from very simple Pro- 

 tists the first animals and the first plants may have arisen. All 

 were still very minute, and it is worth remembering that had 

 there been any scientific spectator after our kind upon the earth 

 during these long ages, he would have lamented the entire absence 

 of life, although the seas were teeming. The simplest forms of 

 life and the protoplasm which Huxley called the physical basis 

 of life will be dealt with in the chapter on Biology in a later 

 section of this work. 



