ON TIIE SEASONAL GROWTH OF PLANTS. 
449 
tudinal fibres embedded in coarse cellular membrane, without divisions 
either horizontally or vertically. 
That this may be the case with some of these plants is probable, not 
only from the uniformly exciting climate of which they are natives, but 
from the rigid character of their exterior, the bark being harsh, and the 
foliage, even in its young and most tender state, is of the toughest 
texture; hence not easily affected by changes of weather. And as the 
fruit of several of them is, like the fronds, successively (not annually) 
produced, there seems to be less necessity for periodical pauses in their 
growth than in the case of trees otherwise constituted. 
How different is it with the tuberous and bulbous-stemmed plants of 
tropical and other countries. Soon as the monsoons or autumnal rains 
set in, they come forth in great vigour, bloom in great beauty, but 
quickly retire from the increasing heat, leaving their seed to be ripened 
and shed in the dry air, while their vital principle reposes unseen in 
the bosom of the new bulb or tuber which has been formed or en¬ 
larged simultaneously with the seed, and in which it remains secure 
till the arid heat is over. This is exemplified in the heemanthus of 
Africa, the tuberose of India, the potato of South America, and the 
snow-drop of Europe. Were these plants unprovided with those sub¬ 
stantial tuberous or bulbous parts, they must inevitably perish during 
the great heats to which their native lands are subject. 
But to return nearer home. We observe in the temperate climate of 
Europe, and where summer and winter follow each other uninter¬ 
ruptedly, the herbs of the field, and the deciduous shrubs of the copse 
and wood, are active and verdant in the first, and stationary and defo¬ 
liated in the last. Some of them continue to grow and retain their 
foliage till destroyed by frost; others, as cultivated bulbs and tubers, the 
ash already mentioned, and many others, stop as soon as their paroxysm 
of growth is over. With respect to those which are arrested by frost 
(and chiefly exotics), their stopping is easily accounted for, namely a 
coagulation of their juices which stays the current, and consequently 
checks all distension of the membranes and vessels. But regarding; 
those trees and shrubs which cease growing while the weather is genial, 
and, as often happens, both moist and warm, we can come to no other 
conclusion concerning them but to presume that, after a winter’s rest, 
there is a certain division of the system prepared and destined to be 
developed, and, when this is completed, the season of rest recommences. 
This is very evident in bulbs and tubers, whether cultivated in the 
flower or kitchen garden : a hyacinth ceases growth before Midsummer, 
and a Spanish onion very soon after; nor can either of these be 
prompted again into action until they have had a period of rest. In 
VOL. IV.—NO. LIV. 3 I) 
