ACORNS 69 



the plumule having a protective membranous coating of 

 the sarcolemma variety and the radicle and seed being now 

 negatively charged, a positive charge would be communi- 

 cated to the plumule to stimulate upward growth ; the 

 arrangement being, like the resinous secretion of leaf buds, 

 a temporary measure. 



With the seed coat away and the seed opened up the 

 collar was found to have increased in size and thickness ; 

 otherwise it resembled Figure 31. 



The plumule from |-inch above soil was as green as the 

 leaves but brown near its base. 



And here, I think, one fact stands out prominently. 

 When the seed is planted or potted with the apex pointing 

 downwards the plumule is not compelled to curve upwards 

 to the light, but owing to the seed splitting is able to grow 

 upwards in a straight Kne and emerge at the base of the 

 seed. This facility of movement does not, however, seem 

 to extend to the radicle which, when the seed is planted 

 apex upwards cannot issue from the base but is forced to 

 emerge from the top and curve its way downwards. 



f/j.JSf 



When the seed is planted in a horizontal position the 

 manner of growth is illustrated by Figure 30. 



Another note which should be taken is that although all 

 these seeds were potted at the same time and under exactly 

 the same conditions the size and vigour of the seedlings 

 presented considerable variation. The reason, as I found 

 by experiment, was that the embryo in them all had not 

 undergone uniform development before they fell from the 



