VARYING COLOURS OF PLANTS. 123 
colour in the flowers of various seasons. Spring 
is characterized by its peculiarly light and fresh 
tints of colour; Summer, by its brillianey and 
variety of contrast; and Autumn, by the subdued 
and mellow tones in which all vegetable nature 
seems steeped. These beautiful changes of aspect 
are, doubtless, connected with some physical cause, 
and must not be looked at simply as matters of 
interest only to the eye, or to the artist. As 
faithful historians of plant history, it becomes us 
to ask what is the cause of them. 
There can, we believe, be but little doubt they 
are connected with some peculiar difference in 
the nature and quality of sunlight at these dif- 
ferent seasons. Merely to recal to mind the pe- 
culiar tones of the sky at these different seasons, 
would suffice to supply us, after a rude manner, 
with this conjecture. What early riser but 
knows the cold, pale, and almost ghastly look of a 
March morning? and during the day the pecu- 
liar whiteness of the sky must be familiar to 
every observer. In summer, deeper tints accom- 
pany the rising and the setting of the sun, anda 
bright glow seems during the day to rest on every 
living and inanimate object. Autumn takes on a 
