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Show 24 CIRCUMNUTATION OF SEEDLINGS. CnAP. I. In Fig. 13 its course is shown from 6.45 A.M. on June 17th, to 7.40 A.M. on the following mornFig. 13. ! / .SOi,.)>/1 p.m. : 17t1~ f I :1 !; jj :: :::: f! il u J ing; and we see that during the daytime, in the course of 11 h. 15 m., it travelled thrice down and twice up. After 5.45 P.M. it moved rapidly downwards, and in an hour or two depended vertically; 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 continued to rise until 8 A.M., when they stood almost horizontally. Their movement was traced during the whole of this day and until the next morning ; but a tracing is not given, as it was closely similar to Fig. 13, excepting that the lines were more zigzag. The cotyledons moved 7 times, either upwards or downwards; and at about 4 P.M. the great nocturnal sinking movement commenced. Another seedling was observed in a similar ma.nner during nearly tP,''IO'(t.m. 2·i h., but with the difference that the hypocoty l was left free. Tho movement also was less magnificcl. l3etween 8.12 A.M. and 5 P.M. on the 18th, the apex of tho cotyledon moved 7 times upwards or Oxatis rosea: circumnutation of cotyledons, the hypocotyl being secured to a stick; illuminated from above. Figure here given one-half of original scale. downwards (Fig. 14).. The nocturnal sinking movement, which is merely a great increaf3e of one of the diurnal oscillations, commenced about 4 P.M. Oxalis Valdiviana.-This species is interesting, us the coty- CIIAr. I. OXALIS. lcdons rise perpendicularly upwards at night so as to come into close contact, instead of sinking vertically downwards, as in the case of 0 .. r·osl'r~· A glass filament was fixed to a cotyledon, ·17 of an mch m length, and the hypocotyl was left free. On :;oll.m. Fig. 14. ll 0 t.r.f'J/'a4m, .. 1ttiJ• " p~ C 1 11 040 a.m.1.9 .~ '~ I I ! + I I I I I I I I I I I I 'I '-.J O.t:alis rosea: conjoint circumnutation of the cotyledons and hypocotyl, traced from 8.12 A.M. on June 18th to 7.30 A.M. 19th. The apex of the cotyledon stood only 3f inches from the vertical glass. Figure ht>re given one-half of original scale. Fi g. 15. ( \ I t : ~ rw::••P~· 'f 6°1:0 a.11t~iG~:\\ 1!; f[• ~~~~. !1 1.0 801 8°3.'ia.n •• wtt•. Oxalis Vuldiviana : conjoint circumnutation of a cotyledon and the hypocotyl, tniced on vertieal glass, during 24 hours. .Figure here given one-half of original scale; seedling illuminated from above. the first day the seedling was placed too far from the vertical glass; so that the tracing was enormously exaggerated and the movement could not be traced when the cotyledon either rose or sank much; but it was clearly seen that the cotyledons rose thrice and fell twice between 8.15 A.M. and 4.15 P.M. Early on the following morning (June 19th) the apex of a cotyledon was |
