CHAP. I. BRASS1CA. 13 



slightly arched hypocotyl had become nearly vertical, a glasa 

 filament was affixed on two occasions near to the base of the 

 basal leg (i.e. the one in connection with the radicle), and its 

 movements were traced in darkness on a horizontal glass. The 

 result was that long lines were formed running in nearly the 

 plane of the vertical arch, due to the early separation of the 

 two legs now freed from pressure ; but as the lines were zigzag, 

 showing lateral movement, the arch must have been circuro- 

 nutating, whilst it was straightening itself by growth along its 

 inner or concave surface. 

 A somewhat different method of observation was next followed : 



Fig. 3. 



Brassica oleracea : circumnutating movement of buried and arched hypo- 

 cotyl (dimly illuminated from above), traced on horizontal glass during 

 45 hours. Movement of bead of filament magnified about 25 times, 

 and here reduced to one-half of original scale. 



as soon as the earth with seeds in a pot began to crack, the 

 surface was removed in parts to the depth of '2 inch ; and a 

 filament was fixed to the basal leg of a buried and arched hypo- 

 cotyl, just above the summit of the radicle. The cotyledons 

 were still almost completely enclosed within the much-cracked 

 seed-coats ; and these were again covered up with damp adhesive 

 eoil pressed pretty firmly down. The movement of the filament 

 was traced (Fig. 3) from 11 A.M. Feb. 5th till 8 A.M. Feb. 7th. 

 "By this latter period the cotyledons had been dragged from 

 beneath the pressed-down earth, but the upper part of the 

 hypocotyl still formed nearly a right angle with the lower part. 

 The tracing stows that the arched hypocotyl tends at this early 



