Transpiration and Water Movement 113 



Under conditions otherwise similar place one plant (or potom- 

 eter) and a standardized evaporimeter in a current of air (an 

 electric fan may be employed), and a similar plant and instru- 

 ment in a quiet atmosphere. Contrast the water-loss after a 

 sufficient interval. 



Guttation. Water freely some potted plants of cabbage or 

 corn with warm water until the temperature of the soil is about 

 35 ; then transfer the pots promptly to a cool room, cover 

 with bell glasses, and after a few hours describe any exudation 

 phenomena noted. 



Leaf structure. Make hand sections of a variety of leaves 

 (at least four types) and compare by microscopic study, es- 

 pecially the epidermis, palisade tissue, and intercellular spaces. 

 The following leaves are suggested : beech, cherry, or ivy ; 

 .rubber plant or rhododendron ; snap-dragon or jewel-weed ; 

 carnation or small cereal ; pine or spruce. Draw in detail one 

 type. 



Examine and compare, if possible, leaves of any variety of 

 small cereal grown under diverse water conditions. Note es- 

 pecially, the width and venation of the leaf, the amount of 

 bloom, and the number and distribution of the stomata. 



Conduction of water. Cut under water several shoots of 

 young sunflowers, castor-oil plants, jewel-weed, corn, and some 

 plants with light-colored flowers (hyacinth, phlox, or other her- 

 baceous plant convenient), and place the cut ends in vessels 

 containing a red dye. After the lapse of an hour or two note 

 the course of the dye through the stem, also into the leaves and 

 petals. With long standing is there more general diffusion of 

 the dye ? Describe the results. 



Remove shoots which have "been in the dye for a very short 

 period (15 minutes to 1 hour), wipe off the surplus dye from 

 the outside with filter paper, and with a sharp knife or razor 

 cut off the stem and examine promptly with the hand lens to 

 ascertain what portion of the bundle is colored. In the case 

 of the sunflower and castor-oil plant is the entire ring colored ? 

 Peel off the bark of the dicotylous plants and examine it for 

 the dye. Draw conclusions, 



