THE WATER-RELATION 97 



from their encysted structure that the nutrition of plants must be 

 solely by substances in solution. The ultimate importance for plants 

 of the water-relation lies then in nutrition. For water is the medium 

 of presentation of the soluble nutriment, which can thus pass through 

 the cell-wall to the active protoplast within. It is in the protoplasts 

 that the plant is able to build up its own organic compounds, using 

 tor that purpose the substances thus acquired. 



