CHAPTER XL VI. 



FURTHER STUDIES ON NUTRITION. 



593. In our former studies on nutrition we found that such 

 plants as the corn, pea, bean, etc., obtain their liquid food 

 through the medium of root hairs. The liverworts and mosses 

 obtain theirs largely through similar outgrowths, the rhizoids, 

 while a majority of the algse, being bathed on all sides by water, 

 absorb liquid food through any part of the surface. We will find 

 it instructive to study some of the different ways in which diverse 

 plants obtain their liquid food. 



594. Nutrition in lemna. — A water plant is illustrated in fig. 412. This 

 is the common duckweed, Lemna trisuka. It is very peculiar in form and in 



m 



Fig. 412. 

 Fronds of the duckweed (Lemna trisulca). 



its mode of growth. Each one of the lateral leaf-like expansions extends out- 

 wards by the elongation of the basal part, which becomes long and slender. 

 Next, two new lateral expansions are formed on these by prolification from near 



314 



