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accidentally broken across the brittle leaf ribs \n handling, 

 or by brushing j:»ast them as they stood near {he sides of 

 the benches ; only the outer portion of the leaf beyond the 

 break was changed in color. It was perfectly evident that 

 the cutting off of the supply of water by the fracture of the 

 ribs, while at the same time evaporation continued, had 

 induced chemical changes in the tips similar to those of a 

 dying leaf. 



A fine specimen of Cladrastis tinctoria, Itaf. July 1 , 

 bore yellow leaves on one side of the tree and green on the 

 other. Tussock moths were abundant, but they did not 

 seem to account for the division of color ; the real cause was 

 that borers had attacked the trunk close to the ground and 

 girdled three-fourths of the circumference. By the middle 

 of August half the limbs, viz., those which bore the yellow 

 leaves, were bare and the leaves of the other half had 

 become yellow. 



Sept. 1, a Fringe tree (Chionanthus) and a flowering- 

 dogwood (Cornus) were changing color; the former to 

 yellow, and the latter to red. Their trunks were riddled 

 by borers ; near the same time a line Tupelo (Nyssa) was 

 aglow with crimson and purple brown ; in this instance 

 borers had attacked the branches and eaten off much of the 

 bark on the principal limbs. 



A red maple when seen, had changed to a yellow hue, 

 excepting one branch which was crimson and in strong con- 

 trast with the bright yellow. It was found that at the 

 bottom where it formed a fork with another limb it was 

 deformed by a knot much larger than the stem. This de- 

 formity, probably originally caused by an insect, impeded 

 the circulation of sap with the result of a change in color. 

 The singular appearance may have occurred in a previous 

 season, and would be likely to be repeated in the future. 

 A Circidiphyllum of a prevailing yellow color, though red- 

 dish at the top, had a single lower branch of a crimson 

 })urple I Two months before, the gardener at the sugges- 



