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tropaeoloides, but certainly belonging to the above variety) they
rose only from 5o to 15o above the horizon. The pulvinus is developed
imperfectly and to an extremely variable degree, so that apparently it is
tending towards abortion. No such case has hitherto, we believe, been
described. It is coloured green from its cells containing chlorophyll; and
it is seated nearly in the middle of the petiole, instead of at the upper
end as in all the other species. The nocturnal movement is effected partly
by its aid, and partly by the growth of the upper part of the petiole as in
the case of plants destitute of a pulvinus. From these several reasons and
from our having partially traced the development of the pulvinus from an
early age, the case seems worth describing in some detail.
[page 119]
[When the cotyledons of O. corniculata were dissected out of a seed from
which they would soon have naturally emerged, no trace of a pulvinus could
be detected; and all the cells forming the short petiole, 7 in number in a
longitudinal row, were of nearly equal size.


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