PLANTS THAT GO TO SLEEP 163 
trees are not yet sufficiently rested to arouse them- 
selves to a new season of work; or waking, they 
realise that it is but an imitation of spring. Can 
they then tell the difference between time and time? 
Warmer temperature alone does not make plants 
awake. Take the instance of the snowdrop: In 
the bulb of the snowdrop are the rudiments of its 
flowers and leaves; force the bloom of the plant, by 
means of artificial heat, in December, and the re- 
sult is a weak, sickly flower: the plant has not had 
sufficient sleep to regain the strength spent during 
the preceding season. But leave the snowdrop to 
slumber on, as is its habit; in January or February, 
whether the temperature be mild or just above the 
freezing-point, the plant is rested, and the fresh 
flowers appear! 
Plants seem to understand just when it is neces- 
sary for them to close up and take a vacation. 
Those which live in ponds dry up and sink to the 
bottom of the water for rest; those on the hot, dry 
deserts fold their arms and go to sleep, like the 
Rose of Jericho; but all of these, with a seeming 
appreciation of periods of time, are ready to come 
forth when the season is ready for them and when 
their plant-instinct tells them that outside condi- 
tions will permit them to bloom with safety. 
All seeds, bulbs, and tubers, as well as growing 
