84 BOARD OF AGRICULTURE. 



have been found. Copper has frequently been observed in vege- 

 table products used for food, and, what is very singular, the 

 metal lias recently been discovered in the feathers of birds, and 

 some of the tints in the plumage are due to its presence. The 

 fluorine which is found in the enamel of teeth in men and ani- 

 mals, comes from plants, as does also the manganese which 

 accompanies iron in the blood. Aluminium, the metal which, 

 within a few years, has been regarded with special interest, as of 

 great service in the arts, has been found in certain species of 

 Lycopodium, and zinc has been found in the Viola caliminaria, 

 a plant common in some sections of France. Bromine and 

 iodine are found in the marine algce or sea-weeds, and for a long 

 time all of these important substances, employed in medicine 

 and the arts, were derived from sea plants cast upon the shore by 

 the waves. 



The organic constituents of plants, elaborated or formed from 

 combinations of the elements, carbon, hydrogen, nitrogen and 

 oxygen, make up the largest portion of their bulk, and therefore 

 must be regarded as of essential importance as food. Before 

 considering the sources and value of these agents to vegetable 

 structures, it will be interesting to examine briefly the condi- 

 tions under which plants start into existence, and the forces or 

 agents which are involved in developing and sustaining the 

 embryo before the plant has the power of seeking its own food. 



In all the changes and evolutions constantly going forward in 

 the vegetable world, the sunbeam plays a most important part. 

 Analysis of a sunbeam shows that it possesses three distinct 

 functions or powers. It is capable of supplying light and heat, 

 and also it has actinic force, or the capability of producing 

 chemical decomposition and recomposition. Upon the chemical 

 influence of the sun's rays depends the germination cf seeds 

 as well as the growth of the plant. We bury the seed in the 

 ground and shut it out from the influence of light, but we do 

 not place it beyond the reach of the sun's actinic influence, for 

 that penetrates like heat to the little earthy couch where the 

 embryo plant lies hid, and arouses it into life. Light, or the 

 luminous rays of the sun, so important to the well-being of the 

 plant, is actually inimical to the excitation of vitality in the 

 seed. How singular is this fact ! A series of carefully con- 

 ducted experiments have proved that seeds will not germinate 



