Suggestions for Laboratory and Field Work to Precede 

 Chapter Fourteen 



1. Demonstration of imbibition with gelatin, wood, and a dry 

 leaf. 



2. Demonstration of osmosis with thistle tube and animal mem- 

 brane ; or with diffusion shell or porous cup ; or with carrot root 

 and glass tube. 



3. Study the root system of a seedling or weed. Note primary, 

 secondary, and adventitious roots. Make a drawing of the root 

 system. 



4. In the field, study the roots of some plants growing in dry 

 sand ; in clay ; and in swampy low ground. 



5. Study distribution and development of root hairs in seedlings. 

 Wheat and oat seedlings are very satisfactory for this purpose. 



6. With a microscope examine a young root. Try to make out 

 the root cap ; the epidermis ; the cortex ; the vascular axis. 



7. Longitudinal sections of a root tip will show stages in cell 

 division and cell enlargement. Note changes in nucleus, cytoplasm, 

 and vacuole. 



i6s 



