42 THE SURVIVAL OF THE UNLIKE. [l. 



sessile or stationary plants were undoubtedly stemless. 

 As the waters increased in depth, and plants were driven 

 farther and farther from their stai-ting points by the 

 struggle for place and the disseminating influence of 

 wind and waves, the plant body became more and more 

 elongated. Whilst the plant undoubtedly still absorbed 

 food tln'oughout its entire periphery, it nevertheless 

 began to differentiate into organs. The area chiefl\' 

 concerned in food -gathering became broadened into a 

 thallus, a constricted or stem -like portion tended to 

 develop below, and the entire structure anchored itseli" 

 to the rock by a holdfast or grapple. This holdfast or 

 so-called root of most of our present sea -weeds is chiefly 

 a means of holding the plant in place, and it probably 

 absorbs very little food. As plants emerged into 

 amphibian life, however, the foliar portion was less and 

 less thrown into contact with food, and thei-e was more 

 and more demand upon the grapple wiiich was andiored 

 in the soil. The foliage gradually developed into organs 

 for absorbing gases, and the root was fon^ed to absorb 

 the liquids which the plant needed. I do not mean to 

 say that there is any genetic connection between the sea- 

 weeds and the higher plants, or that the roots of the two 

 are homologous; but to simply state the fact that, in 

 point of time, the hold-fast root developed before the 

 feeding-root did, and that this change was i)lainly one 

 of adaptation. Specialized forms of flowci-ing plants, 

 which inhabit water, still show a root system which is 

 little more than an anchor, and the foliage actively 

 absorbs water. The same environmental circumstances 

 are thus seen to have developed organs of similar physi- 

 ological character in widely remote times and in diverse 

 lines of the plant evolution. "As the soil slowly became 



