GENERAL BIOLOGY 



c. Plant Turgor. 



Cut off three leaves and place the cut end of one in a satu- 

 rated solution of sodium chlorate, of another in tap water, and 

 leave the third in the air. At the end of one hour compare and ex- 

 plain results. 



d. Demonstration of Root Pressure. 



Cut off the stem of a vigorous plant 1-2 inches above the ground ; 

 attach to the stump by a tight-fitting rubber tube an S-shaped 

 glass tube with one limb drawn out into a long capillary tube, and 

 with oil in the loop of the S to prevent evaporation ; water the 

 plant and observe the rise of sap (or oil) in the capillary tube. 



e. Demonstration of Water Movement. 



Rate and Path of Ascent. Cut under water a colorless shoot and 

 transfer the cut end to a strong aqueous solution of Eosin; ob- 

 serve and time the rise of color in the nbro-vascular bundles to 

 the leaf. Cut sections of the shoot and observe where the color 

 occurs. 

 Describe results. 



f. Demonstration of Transpiration. 



1. Take a vigorous potted plant and cover the pot and soil with 

 waterproof coverings, so that all loss of water must be through the 

 stem and leaves. Weigh the plant on a good balance at intervals 

 and tabulate the loss through two or three days. 



2. Apply to the upper and under surfaces of a leaf discs of 

 filter paper which has been treated with cobalt chloride (Ganong, 

 p. 190). In the presence of moisture the blue discs turn red. 

 Where is transpiration most active? Where are stomata most num- 

 erous. 



II. IRRITABILITY. 



i. Demonstration of Geotropism. 



a. Place well-soaked seeds of bean and corn in different posi- 

 tions on a sheet of cork covered with cotton flannel and fasten 

 them in place by pins stuck around them. Set the sheet of cork on 

 edge in a glass jar containing 1-2 inches of water; cover jar tightly 

 and set in a warm place. Observe from day to day the direction of 

 growth of roots and stems. After this direction is well estab- 



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