'THE STEM AND BEANCHES. 



177 



tnosi probable answer to that question we owe, 

 not to any professional botanist, but to our 

 great philosopher, Mr. Herbert Spencer. 



The simplest and earliest plants, we sawj 

 Were mere small floating cells, endowed with 

 active chlorophyll. Next in the u^Ward order 

 of evolution came rows of such cells, arranged 

 in long lines, hke hairs or threads, or like 

 pearls in a necklace, 

 as in the green ooze 

 of ponds and lake- 

 lets. Above these 

 simple plants, again , 

 come flat expanded 

 collections of cells, 

 as in the fronds of 

 seaweeds. Now, all 

 these kinds of plant 

 are stemless. But 

 suppose in such a 

 plant as the last, 

 one frond or leaf 

 took to growing out 



of the middle of another, as it actually does 

 in many instances, we should get the beginning 

 of a compound plant, many-leaved, and with a 

 sort of early or nascent stem, formed by the 

 part that was common to many of the leaves, 

 like a midrib. The accompanying diagram 

 (Fig. 49) will make this clearer than any amount 

 of description could possibly make it. Starting 

 from such a point, certain plants would soon 

 find they were thus enabled to overtop others, 

 and to obtain freer access to light and carbonic 



12 



riO. 40.— FIRST STEPS IN THE 

 EVOLUTION OF THE STEM. 



