34 



PRACTICAL COURSE IN BOTANY 



32. Recording observations. — For this purpose a page 

 should be ruled off in the notebook of each student, after 

 the model here given, and the facts brought out by the differ- 

 ent experiments set down as observed. 



Number of Seeds Germinated 



Experiment 26. Can seeds have too much moisture ? — Drop a 

 number of dry beans or grains of corn, oats, or other convenient seed, 

 into a vessel with a bedding of cotton or paper that is barely moistened, 

 and an equal number of soaked seeds of the same kind into another vessel 

 with a saturated bedding of the same material. In a third vessel place 

 the same number of soaked seed, covering them partially with water, and 

 in a fourth cover the same number entirely. Label them 1, 2, 3, and 4; 

 keep all together in a warm, even temperature, and observe at intervals 

 of twenty-four hours for a week. What condition as to moisture do 

 you find most favorable to germination ? Would seeds germinate in the 

 entire absence of moisture ? How do you know ? 



Experiment 27. Was it the presence of too much water, or 

 the lack of air caused by it, that interfered with germination 

 IN THE LAST EXPERIMENT? — To answer this question experimentally is 

 not easy, since it is difficult to obtain a complete vacuum without special 

 appliances. The simplest way is to fill with mercury a glass tube 30 

 inches long, closed at one end, and invert it over a small vessel — a tea- 

 cup, or an egg cup will answer — containing mercury enough to cover 

 the bottom to a depth of two or three centimeters (see Appendix, Weights 

 and Measures, for English equivalents.) The tube must be supported in 

 such a way that its lower end will dip into the mercury without touching 

 the bottom of the vessel. With a pair of forceps insert under the mouth of 

 the tube two or three seeds that have been well soaked in water deprived 

 of air by previous boiling. Being lighter than mercury, they will float to 

 the top, where there is a complete absence of air while other conditions 



