22 CIBCUMNUTATION OF SEEDLINGS. Chat. 1 



cotyl was obsers^ed during 28 K as shown in Fig. 11- K moved 

 in all directions; the lines from right and to left in the figure 

 being parallel to the blades of the cotyledons. The actual 

 distance travelled from side to side by the summit of the 

 hypocotyl was about -2 of an inch; but it was impossible to 

 be accurate on this head, as the more obliquely the plant was 

 viewed, after it had moved for some time, the more the distances 

 were exaggerated. 



We endeaToured to observe the circumnutation of the coty- 

 ledons, but as they close together unless kept exposed to a mode- 

 rately bright light, and as the hypocotyl is extremely hehotropic, 

 the necessary arrangements were too 

 troublesome. We shall recur to the noc- 

 turnal or sleep-movements of the cotyle- 

 dons in a future chapter. 



Gossypium (var. Nankin cotton) (Mal- 

 vaceae). — The circumnutation of a hypo- 

 cotyl was observed in the hot-house, but 

 Gossypium: circnmQu- the movement was so much exaggerated 

 tr^ed on tTrizml ^^** *^® ^^^ *^°^ V^s&edi for a time out of 

 tal glass, from 10.30 view. It was, however, manifest that two 

 A.M. to 9.30 A.M. on somewhat irregular ellipses were nearly 

 following morning, completed in 9 h. Another seedling, 



by means of a 6la- i ,..•,. ,, ,, , j j • 



ment fixed across 1 5 m. in height, was then observed duimg 



its summit. More- 23 h.; but the observations were not 



ment of bead of fiia- made at sufficiently short intervals, as 



TwteT -Sillu- ^1^°^ ^y tte few dots in Kg. 12, and the 



minated from above, tracing was not now sufficiently enlarged. 



Nevertheless there could be no doubt 



about the circumnutation of the hypocotyl, which described 



in 12 h. a figure representing three irregular ellipses of unequal 



sizes. 



The cotyledons are in constant movement up and down during 

 the whole day, and as they offer the unusual case of moving 

 downwards late iu the evening and in the early part of the 

 night, many observations were made on them. A filament was 

 fixed along the middle of one, and its movement traced on a 

 vertical glass; but the tracing is not given, as the hypocotyl 

 was not secured, so that it was impossible to distinguish clearly 

 between its movement and that of the cotyledon. The coty- 

 ledons rose from 10.30 a.m. to about 3 p.m. ; they then sank tiu 

 10 P.M., rising, however, greatly in the latter pai-t of the night 



