Trifolium subterraneum.--The blades of the cotyledons on the first day
after germination (Nov. 21st) were not fully expanded, being inclined at
about 35o above the horizon; at night they rose to about 75o. Two days
afterwards the blades at noon were horizontal, with the petioles highly
inclined upwards; and it is remarkable that the nocturnal movement is
almost wholly confined to the blades, being effected by the pulvinus at
their bases; whilst the petioles retain day and night nearly the same
inclination. On this night (Nov. 23rd), and for some few succeeding nights,
the blades rose from a horizontal into a vertical position, and then became
bowed inwards at about an average angle of 10o; so that they had passed
through an angle of 100o. Their tips now almost touched one another, their
bases being slightly divergent. The two blades thus formed a highly
inclined roof over the axis of the seedling. This movement is the same as
that of the terminal leaflet of the tripartite leaves of many species of
Trifolium. After an interval of 8 days (Nov. 29th) the blades were
horizontal during the day, and vertical at night, and now they were no
longer bowed inwards.
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