74. THE AUSTRALIAN NATURALIST. 
Even in our private gardens a number of different 
plants can be examined, such, as for example, the culti- 
vated Broad Bean (Vicia Paba) and the many forms of 
Lupins. If the leaves of the Broad Bean are examined on 
a crisp night it will be found that the leaflets tilt upwards 
and show the under-surface. In Lupins, the leaflets fold 
downwards, something like a half-closed umbrella. 
The leaflets of Tephrosia also fold downwards, and it 
is interesting to note that the petiole droops also, so that 
the plants have the appearance of being wilted. In early 
morning the leaflets re-assume their ordinary position. 
This curious and engaging movement is no doubt depen- 
dent, in a great measure, upon the influence of the solar 
rays. There is something besides this, however, for we 
lind by experiments that the leaflets of Oxalis cornicu- 
latus, growing in pots, kept in a warm room under a bright 
light, do not regain their normal day position until day- 
light appears. Last season I germinated some seeds .of 
Canavalia obtusifolia, and I found that the first leaf above 
the thick fleshy cotyledons, which is simple, as well as the 
next leaf, which is trifoliolate, drooped in the evening 
after sunset to such an extent that the lamina or leaf- 
blade rested on the ground. Soon after sunrise the leaves 
assume their normal or day position again. 
Many other Australian plants are worthy of special 
attention being paid to the movement of the leaves, with 
a view of adding to the list already recorded by Darwin 
and other writers, who have given special attention to 
several species. It has been observed by Darwin that 
plants asleep are in constant motion, due to no light rela- 
tion, which he terms ‘‘ Autonomous movements.’’ ‘‘This,”’ 
he says, ‘‘depends on innate causes, and are adaptive in 
Nature.’’ He has recorded many experiments to show 
that the so-called sleep of plants is protective in its fune- 
tion. By pinning leaves of certain species of Oxalis in 
such a way as to prevent their folding up during the 
night, he also found that all so-treated were killed by cold. 
It has been repeatedly observed that leaves of sensitive 
plants fold up or drop when light becomes too intense, 
This is considered to afford protection to the plant, as the 
oblique angle to sun’s rays prevents the over-illumination to 
a considerable degree, than if the paraheliotropic position 
were maintained. 
(To be continued.) 
