SEEDS AND SEEDLINGS. 



23 



off; (11) section through whole (soaked) seed, to show pocket with 

 root fitting into it (cut between seed-leaves). Also sketch various 

 stages in germination of seeds planted in different positions and at 

 different depths in your jars and boxes. See Fig. 14. 



44. What things are needed to make the seed 

 germinate ? What have been the surroundings of the seeds 

 whose germination you have been studying? Write down 

 these things as they occur to you. The seeds were steeped 

 in water, placed in soil (or sawdust), exposed to light and 

 air, and supplied with a certain amount of warmth. Now, 

 which of these things are absolutely essential for germi- 

 nation ? 



* Can you devise a simple experiment to show that a seed can germi- 

 nate in the air, without any soil or sawdust for the root to grow 

 into? In what condition would the air have to 

 be kept during the experiment ? Get a wide- 

 mouthed glass jar and pour into it enough water 

 to cover the bottom to a depth of an inch or so. 

 Then stick a long pin through a soaked Broad 

 Bean seed and fix it into a cork (or a piece of 

 wood to cover the mouth of the jar), inverting 

 the latter so as to bring the seed into the jar 

 (Fig. 15). The seed will germinate in the moist 

 air. Keep this simple piece of apparatus for 

 later experiments. 



Will a seed germinate if kept dry ? Place some 

 dry seeds in dry sawdust and others in moist 

 sawdust (an inch below the surface) ; compare 

 the results after a week or two. 



45. How to dry Seeds, Seedlings, etc. Fig. 15. 



Are the "dry" seeds sold by the seedsman quite 



dry, or do they contain any water at all? Into a dry test-tube 

 (warm the tube all over to make sure it is quite dry) put a 

 "dry" seed and heat gently over a Bunsen or spirit-lamp. Notice 

 the drops of water which condense in the colder upper part of 

 the tube. Weigh about 20 "dry" seeds, and dry them thoroughly 

 without scorching or charring them at all. This is best done by 

 placing the seeds for a few hours in an oven, or by means of a 

 sand-bath or a water-bath. Then compare the weight of the 

 thoroughly dried pieces and find out the percentage weight of water 

 which the "dry" seeds originally contained (usually about 10 per 



* Throughout this book asterisks are used to indicate a course of 

 experiments which are of fundamental importance. 



