commenced.

Fig. 13. Oxalis rosea: circumnutation of cotyledons, the hypocotyl being
secured to a stick; illuminated from above. Figure here given one-half of
original scale.

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
cotyledon moved 7 times upwards or downwards (Fig. 14). The nocturnal
sinking movement, which is merely a great increase of one of the diurnal
oscillations, commenced about 4 P.M.

Oxalis Valdiviana.--This species is interesting, as the coty-
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ledons rise perpendicularly upwards at night so as to come into close
contact, instead of sinking vertically downwards, as in the case of O.
rosea. A glass filament was fixed to a cotyledon, .17 of an inch in length,
and the hypocotyl was left free. On

Fig. 14. Oxalis 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 3 3/4 inches from the vertical glass. Figure
here given one-half of original scale.

Fig. 15. Oxalis Valdiviana: conjoint circumnutation of a cotyledon and the
hypocotyl, traced on vertical 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