IlVDKdI'llVTE snciETlKS ^^9 



•work of conduction is not so extensive or Jelinite, and 

 tlierefore in such water plants the woody bundles are not 

 so prominently developed as in land plants. 



(4) Redudioii of mechanical tissues. — In the ease of 

 ordinary land plants, certain lirni tissues are developed so 



I'h.. 1i;ii. ( ;ulf\veed iSargasswii), showing tlie tliallus differentiated into stem-like and 

 li-af-lili(.' jiortions, and also the bladder-like floats. — .\tter Bennett and ^Mt'RR.w. 



that the plant may maintain its f(.)rm. These supporting 

 tissues reach their culmination in such forms as trees, 

 "where massive bodies are able to stand upright. It is evi- 

 dent that in the "water there is no st"ich need for rigid suji- 

 porting tissues, as the buoyant po"\ver of "(vater helps to 

 sttpport the pilant. This fact may Ijc illustrated by taking 



