28 PLANT BIOLOGY 



case-knife bean, acorn, horse-chestnut. Squash seeds are excellent 

 for germination studies, because the cotyledons become green and 

 leafy and germination is rapid. Its germination, as also that of the 

 scarlet runner bean, is explained in "Lessons with Plants." Onion 

 is excellent, except that it germinates too slowly. In order to study 

 the root development of germinating plantlets, it is well to pro- 

 vide a deeper box with a glass side against which the seeds are 

 planted. 12. Observe the germination of any common seed 

 about the house premises. When elms, oaks, pines, or maples are 

 abundant, the germination of their seeds may be studied in lawns 

 and along fences. 13. When studying germination, the pupil 

 should note the differences in shape and size between cotyledons 

 and plumule-leaves, and between plumule-leaves and the normal 

 leaves (Fig. 30). Make drawings. 14. Make the tests described 



in the introductory experi- 

 gff*" ' *iss\ <""\ rnents with bean, corn, the 



castor bean, and other seed 



for starch and proteids. Test 



flour, oatmeal, rice, sunflower, 



fi^^^iki&t*. -oj*^ f° ur o'clock, various nuts, and 



flNl^ ■5^&*£*^ n C ^"^- any other seeds obtainable. 



Record your results by ar- 

 Fig. 30. — Muskmelox Seedlings, with ranging the seeds in three 



the unlike seed-leaves and true leaves. classes, I. Much Starch (color 



blackish or purple), 2. Little 

 starch (pale blue or greenish), 3. No starch (brown or yellow). 

 15. Rate of growth of seedlings as affected by differences in tempera- 

 ture. Pack soft wet paper to the depth of an inch in the bottom 

 of four glass bottles or tumblers. Put ten soaked peas or beans into 

 each. Cover each securely and set them in places having different 

 temperatures that vary little. (A furnace room, a room with a 

 stove, a room without stove but reached by sunshine, an unheated 

 room not reached by the sun.) Take the temperatures occasion- 

 ally with a thermometer to find difference in temperature. The 

 tumblers in warm places should be covered very tightly to prevent 

 the germination from being retarded by drying out. Record the 

 number of seeds which sprout in each tumbler within 1 day ; 2 days ; 

 3 days ; 4 days, etc. 16. Is air necessary for the germination and , 

 growth of seedlings ? Place damp blotting paper in the bottom of a 

 bottle and fill it three fourths full of soaked seeds, and close it 

 tightly with a rubber stopper or oiled cork. Prepare a " check 

 experiment" by having another bottle with all conditions the same 

 except that it is covered loosely that air may have access to it, 

 and set the bottles side by side (why keep the bottles together?). 

 Record results as in the preceding experiment. 17. What is- the 



