THE LIFE AND GROWTH OF SEEDLINGS 13 



1907. 

 March 15. The first bud (the plumule) can just be seen 



between the seed-leaves. 



30. The stem of the young shoot has given off two 

 green leaves which are different in shape from 

 the seed-leaves. 



The bean seed is one of the best to grow in moist air, and 

 the pea also answers well. The seed may be suspended in a 

 glass bottle with a wide mouth by means of a blanket pin passing 

 through the cork of the bottle and one of the cotyledons. There 

 should be water at the bottom of the bottle. The bottle should 

 not be tightly corked, for the seed requires air ; at the same time 

 it must be sufficiently tightly corked to allow of the air inside 

 the bottle being kept moist, otherwise growth is very slow. It is 

 best, too, to keep the bottle in the dark, bringing it in to the light 

 from time to time to examine the growth of the radicle, as most 

 roots grow best in darkness. As far as possible the temperature 

 in which the bottle is kept should be even and about the average 

 heat of the room, say 60 F. If exposed to greater heat, the 

 radicle will grow faster, but the temperature should as far as 

 possible be kept the same. Two seeds may be fixed each in a 

 glass bottle, one with the radicle directed downwards, and another 

 with the radicle pointing upwards. As would be expected, the 

 radicle grows downwards in the first case ; in the second, as soon 

 as it has burst the seed-coat and grown a little, it curves and 

 then grows downwards. Under normal conditions roots always 

 grow downwards. Gardeners when sowing seed let it fall as it 

 comes, for they know that in whatever position it happens to 

 lie, the radicle will grow downwards. 



In growing a pea or a bean in moist air, it is easy to show 

 that growth is most active at the apex of the root. This is an 

 experiment that can be set up during a lesson and watched from 

 day to day in a classroom, if the bottles are kept in a cupboard 

 in the room ; they may be examined at stated intervals and 

 a drawing made of the radicle, say every twelve or twenty-four 

 hours. The experiment is as follows : Draw lines 2 millimetres 

 apart in Indian ink across the radicle, an inch and a half in length. 



