The daily morning journal and courier., 1898-11-05
wHY LEAVES TURN coLoR,


 Brllliant-Eued Foliage of Autumn, Dr. Boiling w. Barton, lecturer on botany at the Johns Hopkins univer- slty, said yesterday in regard to the falling of the leaves in autumn and the brilliant colors characteristic of so many of them:-
 "The leaves of most of our trees fall in the autumn, because it would be poor economy on the part of the plant to re- tain them. They would be worn and torn by the cold, the snows, the sleet and the gales of the harsher period of the year. The weight of the snow and sleet would break the limbs, and the winter gales would tear them to shreds of dry them into brittle and useless ap- pendages. Note the trees that hold to their leaves in winter-the evergreens and it will be seen that such leaves are tough and leathery, else reduced to mere needles, as in the pines.
 Most trees, therefore, shed their leaves, cast them off by an act of smputation of sloughing and cover the scar with a layer of cork, which stops bleeding and excludes hurtful of germs. But before they fall they assume the splendid colors for which we are just now watching from day to-day-such wondrous color display as atone in part of the loss of summer and the dreaded sight of blue-nosed winter standing just beyond.
 'The strangest part of these yearly shows of brilliant foliage which nature offers is that it all seems to be without meaning or, as the naturalist would | put it, it has no special biological significance. It is a mere incident in the later life and the death of the leaves. Color in flowers makes of them organs of allurements to in- sects, birds, etc., which visit them for their honey, and, in return, render the service of pollination Color in fruit likewise makes it conspicuous and se i cures frse transportation by sundry animals, which thus scatter the seed. But the hues of autumn foliage mean little more in the lives of the plants than do the color of precipitates in the test tubes of the chemist.
 "To understand these color changes in the dying leaf we must know some thing of the purpose and function of healthy, active leaves. This function is not, as is so often said, to give shade, 1 whether to the plant itself or to man and beast. If they shade the roots and so economize water this is only by the way, and not the important role they play in the life of the plant.
 ''The plant gets it's food from the earth and the air. These are the raw | materials, salt of the soil dissolved in water and carbonic acid gas free in the atmosphere. These simple sub- stances are received in the leaves and spread out with the green substances 1 of the leaf cells to the action of the i suns rays, and are thus converted into | the complex organic products upon which the plant depends for it's growth | and upon which animals can live. The l leaf green or chlorophyll is the sub- stance upon which all this complicated chemistry depends, and has, therefore { been spoken of as the most important of all known compounds, for life as we know it could not exist without it. Without light however, and a certain high temperature the chlorophyll would avail nothing.
 Leaves may be likened rot inaptly to factory or kitchen, or yet to a | laboratory, operating only in summer time when the sun is bright and the air is warm. Then it is that number of definite products are manufactured and transported back through leaf stalk and stem to parts where they may be immediately needed for growth else to be stored for future use
 AS autumn comes on, the nights grow chill and conditions become un- favorable preparations are set on foot to stop work and to destroy the factory At this period the factory is more or less filled with manufactured goods and of waste or accidental products, the more important ones of which are to be removed and saved before the factory goes The most expensive of all there is the chorophyll. This weak starch, sugar, etc, is to be carried into the body of the plant. But they are not transmissible in their present form. They must be changed into soluble if not simpler substances, and so removed to the places of storage. In this break ing up of the chlorophyll especially new products arise, such as microscopic oil drops and certain fine granular bodies. These refract the light and are the cause of the color in the leaves, together with other coloring matters dissolved in the cell sap In a word, we may say that the color of fall