24 



CIECUMNUTATION OF SEEDLINGS. Chap. 1. 



In Fig. 13 ils course is shown from 6.45 a.m. on June 17th, to 



7.40 A.M. on the following morn- 

 ing ; and we see that during tho 

 daytime, in the course of 11 h. 

 15 m., it travelled thrice dowji 

 and twice up. After 5.45 p.m. it 

 moved rapidly downwards, and 

 in an hour or two depended verti- 

 cally ; it thus remained all night 

 asleep. This position could not 

 be represented on the vertical 

 glass nor in the figure here given. 

 By 6.40 A.M. on the following 

 morning (18th) both cotyledons 

 had risen greatly, and they con- 

 tinued to rise until 8 a.m., when 

 they stood almost horizontally. 

 Their movement was traced dur- 

 ing the whole of this day and 

 until the next morning ; but a 

 tracing is not given, as it was 

 closely similar to Fig. 13, except- 

 ing that the Unes were more 

 zigzag. The cotyledons moved 

 7 times, either upwards or down- 

 wards ; and at about 4 p.m. the 

 great nocturnal sinking move- 

 ment commenced. 



Another seedling was observed 

 in a similar manner during nearly 

 24 h., but with the difference that 

 the hypocotyl was left free. The 

 movement also was less magnified. 

 Between 8.12 a.m. and 5 p.m. on 

 the 18th, the apex of the cotyle- 

 don moved 7 times upwards or 

 downwards (Fig. 14). The noc- 

 turnal sinking movement, which 

 is merely a great increase of one 

 of the diurnal oscillations, com- 

 menced about 4 P.M. 

 Oxalk Va!diviana.—l\\is species is interesting, as the coty- 



8°30^a.7n. 



u 



Oxalis rosea : circuninutation of 

 cotyledons, the hypocotyl being 

 secured to a stick ; illumina- 

 ted from above. Figure here 

 given one-harf of original scale. 



