GERMINATION AND GROWTH 



47 



Practical Questions 



1. Do the cotyledons, as a general thing, resemble the mature leaves of 

 the same plants ? 



2. Name some plants in which you have observed differences, and ac- 

 count for them ; could convenience of packing in the seed coats, for in- 

 stance, or of getting out of them, have any bearing on the matter ? 



3. Does the position in which seeds are planted in the ground have 

 anything to do with the position of the seedlings as they appear above the 

 surface ? 



4. Is this fact of any importance to the farmer ? 



5. Will grain that has begun to germinate make good meal or flour? 

 Why? (27,36; Exp. 25.) 



IV. GROWTH 



MATERIAL. Two young potted plants ; some lily or hyacinth bulbs ; 

 seedlings of different kinds, some with well- 

 developed taproots, apple, cotton, and maple 

 are good examples. 



APPLIANCES. A small flat dish, some mer- 

 cury, and a piece of cork. 



EXPERIMENT 34. How DOES THE ROOT IN- 

 CREASE IN LENGTH ? Mark off the root of a very 

 young corn seedling into sections by moistening a 

 piece of sewing thread with indelible ink and 

 applying it to the surface of the root at intervals 

 of about two millimeters (-fa of an inch), or by 

 tying a thread lightly around it at the same inter- 

 vals. Lay the seedling on a moist bedding be- 

 tween two panes of glass kept apart by a sliver of 

 wood to prevent their injuring the root by pressure. 

 Watch for a day or two, and you will see that 

 growth takes place from a point just back of the 

 tip (Figs. 61, 62). 



Mark off a seedling of the bean in the same 

 way and watch to see whether it increases in the same manner as the corn. 



EXPERIMENT 35. How DOES THE STEM INCREASE IN LENGTH ? Mark 

 off a portion of the stem of a bean seedling as explained in the last experi- 

 ment, and find out how it grows. Allow a seedling to develop until it 

 has put forth several leaves and measure daily the spaces between them. 

 Label these spaces in your drawings, " intornodes," and the points where the 

 leaves are attached, " nodes." Does an internode stop growing when the 



FIGS. 61, 62. Seed- 

 ling of corn, marked to 

 show region of growth : 

 61, early stage of germi- 

 nation ; 62, later stage. 



