362 State Horticultural Society. 



present, but it is complex in its quality, and its effects are various, de- 

 pending on its own inner differences, and upon the nature of the objects 

 upon which it impinges. Ui>on the retina of the eye it gives us the sen- 

 sation of light. P*assed through a prism it is partially decomposed, and 

 some of its fractions give use the sensation of the various colors of the 

 lainbow, while others do not affect the optic nerve at all. This radiation 

 as it impinges on matter is partly transformed into heat, and thus raises 

 its temperature. On certain objects it brings about chemical changes, 

 that is, the radiant energy is transformed into chemical energy. It is 

 this that is manifested in photography, and it is this that effects the pro- 

 duction of starch in the cells of the leaf. While nearly all parts of this 

 energy coming from the sun can bring about this formation of starch, 

 those rays that appear to the eye as yellow light arc the most efficient. 

 The so-called chemical rays are much' less effective. 



This marvelous sun-force doubtless performs other functions less 

 apparent, but as the source of the heat and chemical energy, without 

 which plant growth would be impossible, it is the pre-eminent factor in 

 agriculture, for plant production is the basis of animal production also. 



Wonderful and complex as are the elaborations of nature in plant 

 growth, they are exceeded by those of animal economy. An animal body 

 is a complex mechanism, self-constructive, self-repairing, automatic. It 

 obtains its energy from food and oxygen instead of directly from the sun. 

 This energy is manifested in the manifold activities of the animal organ- 

 ism, such as muscular movements both externally and internally applied, 

 the vital processes of digestion, assimilation, secretion, excretion, etc.. 

 and probably in any acts of mentality or consciousness. In digestion the 

 complex constituents of foods are resolved into simpler ones by the action 

 of chemical agents in the digestive fluids, and in assimilation these prod- 

 ucts of digestion are by still more mysterious chemistry synthesized to the 

 tissues peculiar to the animal. By the vital action of the organism, sub- 

 stances in the tissues and fluids are utilized in providing the energy for 

 the various processes of bodily activity, and are finally changed to water 

 and carbon dioxide in large part, that is. to the very substances with 

 which the plants started to build up their tissues. So the cycle of 

 nature is completed, and through it all, she has been carrying out on the 

 farm, in her animal and vegetable laboratories, physical and chemical 

 transformations that man can imitate but feebly, processes that are of 

 extreme delicacy, and at the same time performed on a gigantic scale. 



Such may be said to be the normal state, normal from our point of 

 view, but with the advent of diseases of plants or animals we see intro- 

 duced by nature additional complications in the processes of her labora- 

 tory, complications that the agriculturist must make haste to master and 



