Columbian Horticultural Soc, Washingto7i. 323 



the seed, yielded fruit in a fewer number of years than the 

 preceding one, and that the graft never bloomed sooner 

 than the parent stock from which it had been taken. He 

 thought these experiments should be made, though they 

 might not redound to the advantage of the present genera- 

 tion, because we should be influenced by more patriotic 

 and liberal sentiments, and labor not for ourselves alone, 

 but for those who were to follow us. He then spoke of 

 horticulture as a useful, salutary and peaceful art, and as 

 the last taste that leaves us ; as a science which served to 

 increase our devotional feelings, by unfolding the matchless 

 wisdom of the great Author of Nature in the wonderful 

 organization of the vegetable kingdom ; and touched upon 

 the effect of light upon the leaves of plants, and of the pe- 

 culiar character and importance of these laws in the veg- 

 etable economy. He said that the lovely and gorgeous 

 colors in which the floral world is arrayed, was the result 

 of light, and the variety of colors from its separate rays, 

 each differently reflected. Plants, he said, which have 

 been raised in the shade, if taken into the light, and ex- 

 posed for a short time to the rays of the sun, become as 

 green as those raised in the sun, and when taken into a 

 dark place grow pale and fade in a few days. Leaves are 

 the lungs of plants; they take oxygen from the air, and 

 emit carbonic acid gas, which is composed of oxygen and 

 carbon. While the former goes off, the latter remains, and 

 converts the sap into a sort of pulp, a part of which con- 

 sists of carbon. The pulp passes from the upper to the 

 under side of the leaf The cells where the pulp lodges 

 being yellow, and the carbon of a dark blue, they form to- 

 gether the green color of the leaves and young bark. Noth- 

 ing enfeebles a plant more than the loss of its leaves while 

 growing. Their fall, according to Rennie, previous to 

 winter, " is not caused by cold, but in consequence of the 

 vessels at the root of the leaf-stalk becoming gradually 

 rigid and obstructed so as to prevent the rise of the sap or 

 the return of the pulp." It is believed that the pulp formed 

 from the sap in the leaf, passes back through the leaf- stalk 

 into the bark, and a portion of it through the bark into the 

 very root. It is the }ndp, therefore, and not the saj), that 

 rises and descends in the plant. The pulp cells are sup- 

 posed to be designed as reservoirs for spare nutriment mat- 

 ter, like the fat of animals. Plants always turn their stem 



