658 SELECTIONS FROM ADDRESSES. 



same mysterious process, and from similar, if not the very- 

 same materials ?" 



By visiting the leaves, the sap becomes a very different sub- 

 stance before returning to the stems and the trunk of the tree. 

 It returns thicker, is in a more concentrated form and better 

 adapted to nutrition, after having thrown off its excess of 

 water. This change causes the fruit to become like that of 

 the branches, and leaves, through which the sap last passes. 

 Thus if a sweet apple is engrafted upon a sour tree, the fruit 

 is sweet, because the sap is elaborated or prepared by a sweet 

 branch and leaves. 



Have you investigated the functions of the leaves, and noted 

 the beautiful operations they perform — how they exhale, ab- 

 sorb, and digest? They exhale during the day, and throw off 

 the excess of water in the sap ; this exhalation is different from 

 mere evaporation, and depends upon the state of the tempera- 

 ture, and the air. 



Absorption is performed mainly by the roots ; but if these 

 are defective, the leaf assumes the office ; and you will see the 

 invigorating effect of a shower of rain on the leaves of parched 

 and wilted plants, long before the water could have reached 

 the roots, and been carried up to the leaves. 



Respiration in plants, as in animals, consists in the absorp- 

 tion of oxygen from the air, and giving off of carbonic acid, 

 and is performed mainly by the leaves. 



Digestion consists in the decomposition of carbonic acid by 

 the green tissues of the leaves, under the stimulus of the light, 

 the fixation of the solid carbon and the evolution of the pure 

 oxygen. 



But I will not dwell on these particulars, interesting as they 

 are. The whole vegetable kingdom is filled with wonderful 

 manifestations of the wisdom, power and goodness of God. 

 On whatever side we turn on the farm, there is still something 

 inviting our contemplation ; something to" awaken new senti- 

 ments of gratitude, new emotions of delight. In the morning 

 the sun glances on millions of liquid drops, changing' them 

 into pearls. The questions should arise, How came they 

 there? What unseen power has been at work during the 

 silent night, studding the blades of grass, the bending leaf, 

 and fragrant flower, with these crystal gems ? 



