THE FUNCTIONS OF THE ORGANISM 9 



frequently be found a dark green filamentous plant 

 known as Vaucheria (Fig. 4), so named after the Swiss Vaucheria. 

 theologian and professor, Dr. Jean Vaucher. Structu- 

 rally it consists of a sparingly branched thread, 

 anchored to the substratum by short, branched, 

 colourless filaments. Microscopic examination shows 

 that each filament consists of a colourless wall lined 

 by a viscid substance in which are imbedded very 

 numerous ovoid 

 green particles and 

 a number of small 

 rounded granules. 

 The central space 

 (or spaces) in each 

 thread is occupied 



by a colourless fluid. Jt ^ 4 Young plant 



The wall is in close of Vaucheria ( x 10). 



contact with the 



damp soil, and its external layer is soft and muci- 

 laginous, owing to absorption of the water with which 

 it is in touch. 



Manifestly such substances as occur in the soil, 

 and are themselves soluble in water, might readily 

 be absorbed by the wall, and so be transferred to 

 the interior. Thus not only might the inorganic 

 salts, of which the soil is in the main composed, find 

 entrance, but gases also, which are soluble in water, 

 might be absorbed by the filament. Let us assume 

 for the moment that these bodies are absorbed through 

 the wall ; they would then at once reach the viscid 

 substance lining the inner side of the wall, and might 

 possibly be absorbed by it in its turn and passed on 

 to the solution filling the central cavity or cavities. 

 The viscid lining of the limiting wall is known as 

 protoplasm and the central cavity as the vacuole, 



