THE GEEEN ALG^ (CHLOEOPHYCE^E) 199 



magnification. Plants that have been kept in a closed dish 

 within the laboratory for a few days grow into a heavy moss- 

 like mass and are good material for study. 



Under low-power magnification the whole body may be 

 traced through its intertwining with its neighbors. It 

 branches considerably (Fig. 161), the branches arising irreg- 

 ularly and rebranching to a 

 small extent. The newest 

 branches are the greenest 

 and most active, and as 

 they grow forward older 

 portions may die, thus sep- 

 arating the branches from 

 one another and resulting 

 in the formation of new 

 individuals by 'vegetative 

 reproduction. No cross 

 walls appear in the vege- 

 tative part of the plant; 

 hence the whole plant is a 

 ccenocyte (Sect. 180). 



184. Vaucheria: nutrition. 

 Water may be absorbed 



from the earth upon which 



T _ , . FIG. 161. Branch of a Vaucheria 



vauchena grows. In case plant 



of those Species that live in Considerably enlarged 



the water the food supply 

 is secured as in other floating algae. The abundant chlorophyll 

 suggests considerable ability to manufacture nutrient sub- 

 stances, but this plant is not so well suited to secure abundant 

 exposure to light as is Cladophora. It is to be noted that, living 

 on the land as these plants often do, they do not have the pro- 

 tection against extremes of light and temperature that water 

 algse enjoy ; also that in nature Vaucheria plants are found 

 in shaded and otherwise protected places. If direct sunlight 

 falls upon these plants for very long, they are not able to live. 



