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SEEDS AND SEEDLINGS. 



55. Is Air required for Germination? The seeds in 

 your germination jars and boxes are exposed more or less 

 freely to air. It is very easy to find out whether air is essential 

 for germination, by depriving the seeds of air, or by confining 

 seeds in closed vessels containing different quantities of air 

 and comparing the results. 



Take four glass jars, all of the same size, and provided with well- 

 fitting corks (Fig. 17). Fill these jars to different heights with moist 

 sand, marking each jar into five equal parts, and putting into the first 

 jar enough sand to reach the lowest mark ; into the second, sand up 

 to the next mark ; and so on. The fourth jar will thus contain four 



Fig. 17. 



times as much sand, and therefore only a quarter as much air, as the 

 first. Into each jar now place six soaked Beans (or twenty Peas), cork 

 tightly, and seal with plasticine and vaseline. In which jar do the 

 seeds germinate best ? Do the results suggest that germinating seeds 

 cause some change in the air, that they use the air up ? 



After three or four days, carefully remove the cork from one of the 

 jars and lower a lighted taper or match into it : note what happens. 

 Open another of the jars, and dip into it a glass rod which has been 

 dipped into clear lime-water (or baryta-water, made by shaking up 

 some barium hydrate with water and filtering). 



