Atmospheric Changes. 219 



plant growing under favorable conditions, both root and leaf action are well 

 balanced, and regulate one another. Change these conditions, and functional 

 disturbance is soon manifest. An instance of this is seen in the bad suc- 

 cess attending plant-culture in the rooms of dwelling-houses. The air is too 

 dr}', and exhalation from the leaves is not compensated by absorption at 

 the root. An e.xtra supply of water does not remedy the evil ; for the roots 

 are not capable of pumping up the amount required. In short, the equilib- 

 rium necessary to health has been disturbed, and the plant languishes. In 

 the case of our vines, we will suppose that a warm, moist atmosphere has 

 excited the plant to vigorous growth. Suddenly the amount of moisture in 

 the atmosphere is largely reduced ; excessive reduction of temperature fol- 

 lows, and the leaves of our vine find themselves surrounded by cold, dry 

 air : but, at the same time, the conditions at the roots remain unchanged ; 

 these are surrounded by moist earth at a temperature perhaps thirty degrees 

 higher than that of the air. The conditions of healthy growth have now 

 been reversed, the delicate tissues of the leaves and fruit become dis- 

 organized, and the floating spores of mildew find speedy opportunities 

 for their ravages. 



As a remedy for these evils, the planting of belts of trees is suggested 

 as barriers to the sweep of drying winds, and as condensers and retainers 

 of moisture ; and also the use of a peculiar covered trellis, described and 

 figured by William Saunders, Superintendent of the Public Garden at Wash- 

 ington, in the Agricultural Report for 1861.* 



With regard to tree-planting, we hope the subject will be agitated until 

 practical results follow. By the wholesale destruction of the forests, we, or 

 rather our ancestors, have changed essentially the climate of the country, 

 and for the worse. The disastrous effects of our improvidence are now very 

 apparent. Prolonged droughts, and an extreme range of temperature, are 

 not uncommon in all parts of the country. Many fruits, once easily pro- 

 duced, now fail, or are uncertain, with us. Many years ago, when the 

 country was thinly settled, the orange was a sure crop along the coast, in 

 Georgia, Alabama, Mississippi, and other States ; and the trees attained 



* Mr. Saunders has had this trellis in use for many years, and has always found it effectual. It is very 

 simple in construction, and well worthy of a trial ; and, moreover, we can now pretty well understand why 

 it should tend to preserve the health of tiie vines. 



