24 



PHYSIOLOGY. 



50. Plants take liquid food from the soil. — From these ex- 

 periments then we judge that such plants take up the food they 

 receive from the soil in the form of a liquid, the elements being 

 in solution in water. 



If we recur now to the experiments which were performed with 

 the salt solution in producing plasmolysis in the cells of spirogyra, 

 in the cells of the beet or corn, and in the root hairs of the corn 

 and bean seedlings, and the way in which these cells become tur- 

 gid again when the salt solution is removed and they are again 

 bathed with water, we will have an explanation of the way in 

 which plants take up nutrient solutions of food material through 

 their roots. 



51. How food solutions are carried into the plant. — We can 



Fig. 29. 

 Section of corn root, showing rhizoids formed from elongated epidermal cells. 



see how the root hairs are able to take up solutions of plant food, 

 and we must next turn our attention to the way in which these 



