Vegetable Phjsiology. 279 



Rose Apple, and the Guava, are the succulent berries of shrubs 

 nf this order, as is also the Pomegranate. Cajeput oil is made 

 from the leaves of an Indian species. It is considered a good 

 external application for the cure of Rheumatism, and was once 

 thought a specific for Cholera. Few Myrtaceae are found in 

 other than warm climates. South America produces a great 

 number of species, and many are natives of New Holland and 

 the South Sea Islands. 



VEGETABLE PHYSIOLOGY. 



NUMBER SEVER 



ABSORPTION OF FLUID BY LEAVES. 



Besides being the special organs of exhalation, the leaves of 

 plants are capable of supplying in some degree the functions 

 of the roots, when these are in any way prevented from per- 

 forming their appropriate office. The fact that leaves as well 

 as roots are capable of absorption is easily shown. Every one 

 knows that when plants have suffered from lack of water, or 

 are faded from excess of light and heat, they will rapidly re- 

 vive, if their leaves are moistened, though no fluid has been 

 supplied to the roots. From numerous experiments, it appears 

 certain that the leaves of trees and shrubs absorb most when 

 their lower side is placed in contact with the water, while those 

 of herbaceous plants abstract most by their upper surface, or 

 equally by both. Thus, leaves of the White Mulberry, placed 

 with their upper side in water, faded on the fifth day ; while 

 those which absorbed by their lower surface remained fresh 

 nearly six months. This effect was, however, no doubt due 

 in part to the greater degree of obstruction to the loss of fluid 

 by transpiration in the second case than the first, the stomata 

 being principally situated on the lower surface. But in exper- 

 iments on other plants in which they are similarly disposed, 

 the contrary result has been observed. Thus, leaves of the 



