Suggestions for Laboratory and Field Work to Precede 

 Chapter Two 



1. Review: physical and chemical changes; molecules and 

 atoms ; elements and compounds ; solids, liquids, and gases. If 

 the pupils have had no introductory science, a few simple demon- 

 strations should be given to make these topics clear. 



2. Study a complete plant, noting the roots, stems, leaves, 

 flowers, fruits, and seeds. Many of the common weeds show all 

 these parts clearly. Examine the plant, not primarily to learn the 

 names of the parts, but in order to get a conception of it as a living 

 thing that is very different from the air and the soil in which it 

 grows. Find out what the pupils already know concerning the 

 plant's requirements, its manner of growth, and the functions of 

 its several parts. 



3. Study a number of leaves from different plants, and make 

 drawings to illustrate a variety of leaf forms, simple and compound 

 leaves, and the parallel and net arrangements of the veins. Note 

 the thickness, texture, color, and surface in each of the different 

 specimens. Note also that the veins reach every part of the 

 leaf and connect through the petiole with the interior of the plant 

 stem. 



4. Study a skeletonized leaf to make clear the arrangement of 

 veins and their intimate relation to the mesophyll cells. A nastur- 

 tium leaf that has been decolorized in alcohol may be studied under 

 the microscope to show the small veins and the fine ramifications 

 of the vessels. 



5. Dissect a leaf from an Easter lily, live-for-ever, or Wandering 

 Jew. Study especially the relative positions of the epidermis, 

 mesophyll, and veins. 



6. Study with a microscope cells from the epidermis, dis- 

 tinguishing the cell wall, protoplasm, nucleus, cytoplasm, and 

 vacuole. The epidermis from an onion scale is good material 

 for the study of the cell parts. 



7. Draw some cells from a leaf of moss, such as Mnium, after 

 it has been in good light for several hours. Note cell walls and 

 chloroplasts. Staining with a weak iodin solution will show the 

 starch grains within the chloroplasts. 



