ILLINOIS HORTICULTURAL SOCIETY. 287 



air, and i-ctiinis in ashes all that boUiniiS to the soil. Rotting is hut a sUnv tire; ami tlie tree is thus 

 lionest when it gives I)aeli. to nature the materials drawn Ironi nature. 



The in(iuiry then boeomes interesting as to where the atmosphere obtains the vast amount of air 

 food and air driulv necessary to build iip the forests and clotlie the continents with vegetation. A 

 part of tills air food is gathered from the slow conbustion or decay of vegetation on tlie land; but the 

 greater part of this air food of plants comes froin the moist breath of the sea forever breathing over 

 the land and carrying to tlie trees not only tlielr air food but their drlnlv also. The in\ isihie lingers 

 of the atmosphere thus feed the forests and carry to them drink from the sea. 



To illustrate the agency of the ocean in the economy of nature and the growtli of vegetation, tlie 

 lecturer described some of Its clilef characteristics—its great curreuts, whirls, and ceaseless agita- 

 tions— its flows, now rising to the surface and now sinking to invisible depths; all controlled by the 

 great laws of heat and cold, and the dltterences in temperature between Polar and Tropical waters. 

 One of these, the great Gulf Stream, a river in the Sea, was fully described, flowing with vast 

 volume almost round the Atlantic. This gathers up the wood and vegetation constantly borne to the 

 sea by tlie rivers, and sweeps along l!ie immense amount of algea or sea weed, constantly torn loose 

 from their frail moorings. These gradually center towards the middle of the Atlantic. Mariners 

 call this comparatively still part of the Atlantic Ocean, the Sea of Saragossa— a sea in the ocean 

 larger than the valley of tlie Mississippi Hiver. Its surface becomes covered with drift weed, so 

 thick in places that a ship can not sail tlirough it. This vegetation is constantly decaying and 

 throwing oft" its gaseous elements into the air; and loading the air with the food of plants. All 

 oceans and all seas produce similar phenomena. In this way tlie ocean becomes the great Labo- 

 ratory of nature, where the air food of plants is largely eliminated and manufactured. The ocean— 

 never at rest, pulsating and throbbing like the great heart of God round the world— thus puriflcs 

 itself, and thus gives up by its breath and from its life, a part of its own plant life, to feed the 

 vegetation on the land. This breath of the Ocean then— these breathings of the sea— are the winds. 

 At rest, we call them the atmosphere, in motion we call them the wiiuls: when the spirit of the 

 storm is aroused, we call them the hurricane and tornado; coming from the sea to the land we call 

 them the Breath of the ocean on the land. 



The same causes move the winds and give them their circuits, which move the waters of the sea, 

 where this breath of the ocean comes fresh to the land from favorable seas forests grow up and vege- 

 tation grows and blossoms. The winds are thus the express carriers, agents, and servants of the 

 sea, bearing to the land the food and drink of vegetable growths; and the forests through their leaf 

 lungs, in some mysterious way, breathe in and exhale the elements which minister to their growth. 

 This thought was illustrated by reference to wind charts, precipitation of moisture, and the isother- 

 mal lines in North America. Those which come fresh and moist from the ocean to the land confer 

 fertilit)', and forests spring up; those v.iiich become exhausted of their food and moisture make 

 deserts out of fertile plains. The breath of the I'aciflc l)uilds up gnat forests in California; the 

 breath of the Atlantic and the Gulf of Mexico makes the Eastern part of the ilississijipi valley and 

 Xorth America green and rich. The hot breath of torrid ilexico makes our ^^■estern Sahara desert. 



The lecturer then spidic of the manner in which the air feeds and waters trees. The milHoned 

 hosts of the forest leaves hang trembling in the atmosphere. The leaf performs functions similar 

 to the lungs and stomach. It is full ot invisible mouths, which breathe in and exhale the atmos- 

 phere; which take in moisture and air food, and tlirow out poisonous and worn out elements, which 

 the plant has already used, and desires to free itself of. The leaf and every inch of surface soil suck 

 in the rains and dews and nutritious gases. iSoth roots and leaves play important parts in the 

 economy of vegetable growth. The question, somewhat discussed, as to whether plants absorb 

 their air-food directly through their leaf-lungs, or whether it is carried by rain water into tlie soil 

 and thence absorbed into tlie general circulation by means of the roots, aiipertaiiis to the province 

 of vegetable physiology . For the purposes of this lecture it can make no difterence The organic 

 elements of the plant are obtained chiefly from the air, either directly by the leaves or from the soil 

 through the roots. 



The lecturer then passed to man's influence over the forces of nature. lie showed that the condi- 

 tions of the atmosphere necessary lor tree growth were heat, humidity, and light. He argued that 

 man can and <loes control climate and atmospheric influences; and illustrated his position by the 

 eifect of settlement and civilization on the prairies of the "West. Cultivation makes the land dryer; 

 tlie streams run lower; the sjirings dry up; the precipitation of moisture is less, and the absorption 

 of moisture is greater. We all know that the Jlissis-sippi is growing smaller from this cause, as 

 every average often years of the volume of its waters would show. When the whole valley is under 

 cultivation a very marked change in its streams will be noticed. 



Another great ettect is produced by building up or chopping down forests. Tlie history of civili- 

 zation in Europe abilndantly sustains this proposition. Flourishing provinces have been made 

 waste jilaces, and emporiums of trade and seats of empire rendered uninhabitable by the destruction 

 of the Mediterranean woods. Our own virgin soil will no longer produce its great wheat crops, not 

 so much through exhaustion of the soil, as from causes more directly traceable to the laws of mete- 

 orology. 



