DIRECTIONS FOR LABORATORY STUDY. 391 



Study and compare the flower and leaves of the sweet pea 

 (Lathyrus odoratus), apple, fuchsia, and garden lily. 



For the study of primary roots and root hairs, primary stem 

 and primary leaves, germinate Indian corn, scarlet runner or any 

 bean, in clean damp //«£- sawdust, and grow until plants are sev- 

 eral inches high, watching stages of development. 



For forms of stems examine white potato (tuber); onion (bulb); 

 Indian turnip or Cyclamen (corm); morning glory or hop (twin- 

 ing); white clover (creeping). 



For structure of stems, study Indian corn (monocotyledon, with 

 no secondary thickening), cucumber or pumpkin (dicotyledon, 

 with no secondary thickening), and young sunflower (dicotyledon, 

 with secondary thickening). Compare transverse sections. 



For lenticels and the formation of periderm, examine the twigs 

 of plum, cherry, elder or box-elder. 



For buds examine large winter buds of hickory, horsechestnut, 

 or poplar. 



Part II: Physiology. 



1. To show the existence of turgor in the individual cell. (^[ 188.) 

 Mount a bit of Spirogyra under microscope; observe position of 



chlorophyll bands. Irrigate with 5 per cent, solution of salt and 

 note effect. 



(If Spirogyra is not at hand use hairs on stamens of Trades- 

 cantia ; or the epidermis, filled with purple cell sap, from the 

 under side of the leaves of the cultivated Tradescantia (" wander- 

 ing Jew"); or the hairs of geranium leaves.) 



2. To show effect of turgor of cells on rigidity of young parts con- 

 taining no mechanical tissues, (^f 18S.) 



Remove carefully a young plant with vigorous primary root 

 grown in sawdust or sand. Lay in water for a few minutes. 

 Note rigidity. Transfer to 5 per cent, salt solution for a few 

 minutes. Again note rigidity. What has happened? Remove 

 to water again for 15 min. What is the result? 



3. To show the existence of longitudinal tensions of tissues due to 

 unequal gro7vth or turgor, (^[ 259.) 



A. Cut a young internode of elder 10 cm. long, making ends 

 as square as possible. Measure accurately. Remove wood all 

 around and measure pith. Place pith in an atmosphere satu- 



