92 HISTORICAL SKETCH. 



the most precious and beautiful ; and if we have not yet discovered the 

 utihty of but, comparatively, a very small number, still we should gratefully 

 recognize the munificence of the Almighty, and doubt not that the design 

 was as beneficent, as it is immense and incomprehensible. If we look up 

 into the heavens, do we not behold far grander objects of amazement ; for 

 of the millions of illuminated spheres which sparkle in the firmament, we 

 perceive but two which appear to have been formed for our benefit — the 

 Sun and Moon. How fully do we thus comprehend, the sublime signifi- 

 cance of those awful interrogations, which were addressed to the astounded 

 patriarch of Idumea : 



Where wast thou, when I laid the foundations of the Earth? 

 Knowest thou, the ordinances of the Heavens? 



Hawthorn Cottage, ) 



Roxbury, January, 1851. j 



NOTE. 



Sensibility of Plants. — Page 91. 



I was not aware, until within two years, of the remarkable and very conspicuous sensi- 

 bility of the leaves of the Rhododendron, or Rose Bay. In the Spring of 1849, I obtained a 

 very excellent specimen of that unrivalled variety of flowering shrubs, from the Messrs. 

 Hoveys' Nursery ; and I have been astonished, and deeply interested, at the wonderful 

 changes produced in the position of the leaves, by the increase and diminution of the 

 temperature of the air, more especially in the Winter. 



During the period of vegetation, and at all times when the heat reaches 70 degrees of 

 Fahrenheit's thermometer, the terminal leaves of the branches are elevated at an angle of 

 from twenty to thirty degrees above a horizontal line, and their surfaces are flat; but as the 

 temperature diminishes, they gradually droop ; and when the air is cooled as low as twenty, 

 their position is perpendicular, while they simultaneously roll back longitudinally, so far, 

 as that the edges touch, and each becomes a perfect cylinder ; and during this process the 

 color as uniformly becomes darker, until it assumes a dusky green. On the return of a 

 warm day the leaves immediately begin to unroll and to rise, and the color becomes lighter, 

 until it resumes the rich tint peculiar to them when perfectly matured. These changes 

 are as continual and diversified as the variations of the temperature of the atmosphere, and 

 during the coldest months are very great; and are as worthy of attention as they are 

 singular and impressive ; for so regular are they, as to render the plant a very delicate 

 Vegetable Thermometer. 



1 have not seen any allusion to this extraordinary characteristic of the Rhododendron, in 

 any work in which it is described. 



Ahhough some of the most beautiful of the few natural species of this shrub are indige- 

 nous to this country, it is to be regretted that it has been but little cultivated, when in 

 Europe its preeminent claims to admiration have been so universally acknowledged, as to 

 have rendered it a distinguished favorite. This plant and our elegant Kalmia, Azaleas, and 

 Magnolias, now hold such a high rank in the collections of the most precious specimens of 

 the vegetable kingdom in England, that at the last exhibition of the London Horticultural 

 Society, tliey were considered as entitled to precedence. 



