96 THE VEGETABLE WORLD. 
plant in a carriage, observed that the plant closed its folioles, and 
all its leaves drooped as soon as the carriage began to roll over the 
pavement, but by degrees it seemed to recover from its fright, 
became habituated, so to speak, to the movements, its leaves 
resumed their erect position, and its folioles their full expansion. 
Desfontaines now caused the carriage to stop for a time. When 
it resumed its motion the plant responded by dropping its leaves 
as before, but after a time they expanded again, and so continued 
during the remainder of the journey. Shall we not say that here 
there is reflected impression and motive on the part of this singular 
plant? These phenomena of irritability under the influence of 
direct chemical or mechanical action, the plant repeats of itself 
during the night. The Sensitive plant closes its folioles when the 
obscurity of night sets in. 
This habit of folding up its loayés during the night is not con- 
fined to the Sensitive plant exclusively ; it appertains to other 
plants whose leaves occupy different positions during day and night. 
These are the plants to which Linnzus alludes when he writes of the 
sleep of plants. ‘‘ But we must remark,” says De Candolle, “that 
this term, borrowed from the animal kingdom, does not represent 
the same idea in both. In animals sleep indicates a flaccid drooping 
state of the members, of limpness in the articulations; in vege- 
tables it indicates a changed state; but the nocturnal state majD- 
tains the same degree of rigidity and the same constancy as the 
diurnal position. We may break the sleeping leaf rather than 
maintain it in the position which belongs to it during the day.” 
It was in the Bird’s-foot trefoil, the pretty Trigonella ornitho- 
podioides, that Linnzeus remarked for the first time the difference 
between the altitude of the leaves during the day and night. 
Scarcely had he made this remark when he came to the conclusion 
that this phenomenon would be found not to be confined to this 
single plant, but would be found general in vegetable life. From 
that time, every night Linnzus tore himself from sleep, and in 
the silence of nature studied the plants in his garden. At each 
step he discovered a new fact. Each natural fact, when put 
in evidence by a first observation, has been rapidly confirmed by 
crowds of facts quite analogous to the first, and Linnzeus very 8002 
satisfied himself that the change in the position of leaves during 
