ORCHARD NOTKS. 55 



temperature drop below the freezing point, following a period 

 of warm weather. 



A significant fact is that the trees most severely affected were 

 confined to a small group standing in a slight depression that 

 serves as a drain for the slightly higher ground surrounding. 

 The cases of lesser injury also indicate the probable relation 

 of topography and consequent drainage to the injury. Land 

 which collects a greater amount of soil moisture than neighbor- 

 ing areas will, if said moisture is not excessive and other con- 

 ditions are equal, tend to produce in trees growing therein a 

 greater response to temperatures inducing plant activity. 



The records for the winter of 1910-1911 show that from 

 January to the end of March several periods of temperatures 

 high for those months were followed by sudden and rather great 

 drops below the freezing point. The hypothesis is that the 

 warm periods referred to induced considerable activity in some 

 trees, so that when the temperature fell suddenly close to 30 

 degrees Fahr. cleavage of bark from wood occurred by the 

 freezing of the water-containing tissues of the former. The 

 trees responding most actively were those in locations of highest 

 soil moisture content. Those in dryer soil responded slowly 

 enough to suffer no damage. 



