186 



ment of chlorophyll in the cortex of the new tuber, the metabolic 

 changes have been accompanied by no increase of substance. On 

 the contrary, it is probable that, owing to respiration, the dry 

 weight of the parts is less than that of the original piece of tuber. 



Part of the food elaborated and digested in the leaves of the 

 parent plant was translocated to the tuber of which the piece in 

 Figure i was a part. After the portion in question was cut off 

 and placed in the conservatory this stored food began to be redi- 

 gested and translocated to the developing "eye" or bud. There 

 has been, then, merely a transfer of substance from the cells of 

 the old tuber to the cells which ultimately developed the new. 



Normally this awakened bud would presumably have given rise 



to an aerial leafy branch. The causes of its development into a 



tuber are difficult to recognize. Environmental conditions were 



not such as have favored tuberization in recorded experiments, 



and internal causes are still more difficult to assign. 



New York Botanical Garden, 

 July 13, 1906. 



A NEW CHESTNUT DISEASE* 



By William A. Murkill 



A new and very serious disease of our native chestnut is epi- 

 demic in many parts of New York City and threatens to destroy 

 practically all the chestnut trees in this vicinity. A field survey 

 has not yet been undertaken, but the disease is known to occur 

 also in New Jersey, Maryland, the District of Columbia and 

 Virginia. 



An investigation of the disease was begun at the New York 

 Botanical Garden nearly a year ago, and most of the facts regard- 

 ing it are now in our possession. Pure cultures of the fungus 



* Murrill, W. A. A serious chestnut disease. Jour. N. Y. Bot. Garden 7 : 143- 

 153- /• 13-19- June. 1906. 



Merkel, H. W. A deadly fungus on the American chestnut. Ann. Rept. N. Y. 

 Zool. Society 10 : 97-103. July, igo6. [Illust.] 



Murrill, W. A. Further remarks on a serious chestnut disease. Jour. N. Y. 

 Bot. Garden 7: 203-211. / ^j-jo. September, 1906. 



