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able in the fall. No sooner has the new foliage of the year 

 assumed its emerald hue than it begins to show signs of 

 decay in individual cases, the leaves here and there turning- 

 yellow, orange, russet, red, dull purple or purple brown, 

 and falling off. Yellow leaves have been seen on maples 

 even in May. 



Various causes operate to produce the change of color ; 

 the following may be designated : lack of sun and air (ven- 

 tilation), bad drainage, drought, frost, excessive heat, 

 injury to roots, branch or leaf, fungus, blight or other dis- 

 ease, transplanting, rapid evaporation* by drying winds or 

 hot sun, embrace of twining plants, injuries from insects, 

 ripening of the leaf, sudden changes of temperature, forest 

 fires, injuries by storms and other accidents, etc. We shall 

 illustrate some of the foregoing causes of color change from 

 actual observations : 



A potted India Rubber plant was placed into a lal'ger, 

 but closely fitting, decorated pot having no outlet for drain- 

 age. In a short time the leaves began to turn a rich yellow 

 and fall. It was found that there was an accumulation of 

 water in the outer pot from excessive watering, wiiich 

 drained from the inner one, and this had driven out the air 

 necessary for the roots, for the plant speedily recovered 

 with proper drainage. 



Trees, shrubs and herbs with dense foliage are apt to 

 have some of their interior leaves ''damp off" and turn 

 yellow from lack of sufficient sun and air. This is frequently 

 seen in sugar maples, apple trees, currant and gooseberry 

 bushes, and among low plants in shady woods even in 

 early suumier. 



Plants in greenhouses also decay from too much watering 

 during the resting period. The leaves of many gray birches 

 {Betula popuJifolia, Ait.) growing in dry, sandy ground 

 were largely yellow early in July ; the trees were evidently 

 suffering from drought as the month was very hot and dry, 

 A number of herbaceous plants growing in wet places 



