236 ANATOMY AND PHYSIOLOGY Of I'LANTS. 



Thus it is justly remarked, that the upper surface of the leaves in 

 some plants, strongly repels moisture, as in cabbage leaves, where 

 the particles of rain have the appearance of globules of quicksilver. 

 It appears, likewise, from actual experiments, that the leaves of ma'.iy 

 plants, when they were laid with their upper surfaces upon water, 

 withered almost as soon as in the dry air, though the same leaves, 

 when they were placed with their under surfaces upon the water, 

 continued green many days. 



27. The under surface has been proved, by repeated 

 experiments, to be the part particularly destined for 

 absorption. 



28. Admitting this relation of the structure and 

 functions of leaves to be correct, their grand use to the 

 plant, is to assist in supporting vegetable life, by exha- 

 lation on the one hand, and absorption on the other. 



In our remarks on the passage of the fluids from the common 

 vessels to the proper vessels, we have also shown a very impoitant 

 rircnmstance connected with the leaf, wherein it appears, the leaves 

 have the power of secreting from the common juices of the plant, 

 peculiar and sometimes powerful fluids or even substances, as the 

 resin of the fir, the gum of the Egyptian thorn, and so on. 



ON THE REPRODUCTIVE ORGANS. 



1. Having spoken of the root, stem and leaf, we will 

 now analyze the reproductive organs, or those parts 

 which are necessary for the reproduction of the indivi- 

 dual ; viz. the flower and the fruit. 



The parts, therefore, which will come under our present attention, 

 will be, the calyx ; corolla, stamen, pistil, nectary, seed-vessel, feed, 

 and receptacle. 



