PREMATURE FALL OF THE LEAF. 429 



Dr. Schacht describes this more in detail. He 

 says, " The cells at the place of separation are cork, 

 and the scar is subsequently covered with it. The 

 transmission of sap is consequently impeded, and at 

 length entirely cut off, insomuch that the leaf hangs 

 loose, and finally falls." 



But, with much reason, Dr. Berkeley contends 

 that this is not the cause of the phenomenon, but 

 only an efi"ect, by which these cells endeavor to 

 cover the live wood of the tree in such a manner as 

 to prevent the transmission of any morbid matter. 

 This transmission he often observed to be the cause 

 of canker. The fall of the flower and the fruit he 

 considered as belonging to the same class of phe- 

 nomena. It may be said that, in the case of a fruit, 

 death has not taken place ; but it will be seen, upon 

 a moment's reflection, that as far as its relation to 

 the tree is concerned, the fruit has really ceased to 

 live as soon as it stops drawing nutriment from the 

 tree. " The parts have all arrived at maturity, and 

 therefore neither require any more food from the 

 mother plant, nor are they in a condition to make 

 any further interchange," (fermentation having 

 probably commenced) " and separation takes place. 

 The fall of the leaf, considered as a disease^ is when 

 this phenomenon takes place at an improper time, 

 and results either from some constitutional or 

 accidental cause." 



The Flemish Beauty and the Paradise d'Automne 



