28 



Elementary Plant Physiology. 



lowed by the wakening and activity of buds hitherto dormant 

 below. Continue the process until all of the buds have started 

 into activity. The leafy stems of this plant are lateral branches 

 of the fore shoot. Remove the branches as soon as they ap- 

 pear, and follow the development of the main, or fore shoot. 

 In many instances it will take on a lengthened, club-shaped 

 form. Taste the inner portion of the germinated potato. It 

 will be found to have developed a slightly sweetish taste, owing 

 to the conversion of some of the starch 

 into a sugar, probably glucose. Other 

 chemical changes in the tubers make it 

 unsafe to swallow much of the material 

 because of the poisonous action of 

 some of the substances formed. 



20. Influence of temperature 

 upon germination of seeds. Soak 

 a number of seeds of corn (Zea), wheat 

 (Triticuni)i or oats (Avena) in water 

 for a few hours, and then place a dozen 

 in each of four germinating-dishes, or 

 in tumblers wrapped in damp cloth or 

 blotting paper. Place one on a table in 

 the laboratory; another in the cham- 

 ber of an ice box; a third on the 

 blocks of ice in the top of the refriger- 

 ator; and a fourth near a heater or 

 stove, where the temperature will remain about 20 to 25 C. 

 Note the readings of a thermometer in each of these places 

 two or three times for a week. How many of each kind of 

 seed have germinated under the different conditions offered? 

 Do all seeds germinate at the same temperature? 



21. Endurance of high temperatures of seeds. 

 Place twenty air-dried seeds in a small dish, and set in an incu- 

 bator, or in a compartment of an oven kept at about 40 C., 



Fig. 13. Germinating 

 potato showing fore shoots 

 arising from buds near the 

 apical end. After Detmer. 



