92 



HYPOCOTYLS, EPICOTYLS, ETC., CHAP. II. 



wise hypogean. Some seedlings with well-developed 

 radicles were first immersed in a solution of perman- 

 ganate of potassium ; and, judging from the changes 

 of colour (though these were not very clearly defined), 

 the hypocotyl is about *3 inch in length. Straight, 

 thin, black lines of this length were now drawn from 

 the bases of the short petioles along the hypocotyls 



F:g. 59. 



u 



Vicia faba : germinating seeds, suspended in damp air : A, with radicle 

 growing perpendicularly downwards ; B, the same bean after 24 hours 

 and after the radicle has curved itself; r, radicle; 7t, short hypocotyl ; 

 e, epicotyi appearing as a knob in A and as an arch in B ; p, petiole of 

 the cotyledon, the latter enclosed within the seed-coats. 



of 23 germinating seeds, which were pinned to the 

 lids of jars, generally with the hilum downwards, and 

 with their radicles pointing to the centre of the 

 earth. After an interval of from 24 to 48 hours the 

 black lines on the hypocotyls of 16 out of the 23 

 seedlings became distinctly curved, but in very 

 various degrees (namely, with radii between 20 and 



